Matt Wittenrich Live

Miniature Mandarin Beer Mug Diner

Nine-month-old Green Mandarins bred by the author in their sunken beer-mug feeder.

Last year, as my interest in mandarins was being rejuvenated, I searched the internet for recent happenings in the world of the Genus Synchiropus. Beyond the obvious reports of reproduction and rearing, I was interested to know if things were changing in the way aquarists approached feeding their psychedelic but difficult-to-nourish pets. 

One of the best articles I came across was by Marc Levenson’s on melevsreef.com entitled Melev’s Mandarin Diner. At the time, I thought the article and video were quite amazing, but stored the information in the back of my brain thinking it had little application for what I was trying to do. Marc maintains a large reef aquarium and target feeds his mandarins by lowering a jar filled with pellets to the floor of the aquarium. The mandarins have come to recognize the jar with food and are allowed to feed unchallenged by the larger fish in the reef.

Well, nearly a year later I have found a use for this ingenious contraption.

I now had hundreds of juvenile mandarins eating prepared foods. At first, I simply dumped the food in the growout tank and watched as it swirled and floated with the current. I wondered, “Is it ever going to sink?”. As tiny morsels hit the deck they were quickly scarfed up, but maintaining water quality was becoming a challenge.

If I lowered the water flow, nitrogenous waste build up became obvious, but when I increased the flow to flush uneaten food out of the system, the mandarins weren’t getting enough to eat. Aha! The light bulb lit and I recalled Marc's trick. 

I filled tiny glass beakers with food and lowered them into the tank, making sure to spill a little at the entrance. Before long, the little mandarins began to congregate at the entrance of the beaker. Another few weeks went by and the little guys would pile up inside the beakers waiting for the dinner bell to ring. I soon realized I was going to need a bigger beaker. 

I met Marc at this year's MACNA Conference in Atlanta and expressed my thanks for his article. I swore I would try to get a picture of the little mandarins in their diner and although it has taken some time I finally got one. Last night as I was busily trying to get some work done on the computer I looked over to the mandarin tank and realized I forgot to feed them. Some of them were anxiously waiting inside their beer mug diner. No more mess, no water quality issues and best of all, Beer Mug Target-fed Mandarins.

Thanks Marc!

Melev’s Mandarin Diner: http://www.melevsreef.com/mandarin_diner.html

Marine Breeding: From Redfish to Your Fish

The author with an Indian River (Florida) Redfish, part of a breeding population that does not migrate from lagoon to ocean to spawn.

What food and game fish aquaculture can teach us about raising ornamentals

Aquaculture is nothing new. In fact, its origins can be traced back to 2,500 BC when the ancient Egyptians grew tilapia in earthen and stone ponds.

Modern aquaculture has made a wealth of technological advancements in recent decades, and food fish aquaculture has become a major enterprise throughout the world. Although freshwater species such as catfish and salmon rank among the top aquaculture products in the United States there has been great motivation to bring marine species to the forefront of food fish markets.

At first glance, it is hard to imagine that a flounder, an amberjack, a cobia, or even a cod has anything in common with a dainty aquarium fish, but we can learn a surprising amount from the success of aquaculture in these species.

The ocean is an incredible and dynamic scene that sets the stage for some truly unique reproductive strategies. Virtually all reef fish, with a few notable exceptions such as the Banggai Cardinal (Pterapogon kauderni) and the Spiny-tail Damsel, exhibit a bi-partite life cycle where the adults live in close association with the bottom while early larvae are found in the open ocean. Most reef fishes reproduce by casting hundreds or thousands of tiny, buoyant eggs adrift in the ocean.

A group of 18-day-old snook reared by me in collaboration with MOTE marine lab.

With no parental care, the eggs are left to develop, hatch, and if they are lucky, survive to metamorphosis and recruit to the adult population. For years, pelagic spawning species of reef fishes have intimidated most hobbyist breeders and small scale entrepreneurs.

In years past, it was hard to enough to fathom hatching demersal eggs and dealing with pelagic larvae, let alone starting with a pelagic egg. But, food-fish aquaculturists have been doing just this for years. Every species of marine food fish produces pelagic eggs giving us years of information and advancements available in journal articles, magazines, technical reports, conference proceedings and books.

So don’t be intimidated. Look to the foundation that has been cast before us.

 

When is a larva a larva and a fry a fry?

Larval fishes, displaying a wide diversity of form.

My recent blog entry on the microscopic gourami raised a curious question: what is the difference between larvae and fry?

This is a good question and helps illustrates some of the confusion that terminology creates within such a broad field. Is a Blue Tang always Paracanthus hepatus and is a goldfish always gold?

The list of questions could go on and the answers are often ever more challenging. For quite some time I thought the difference was as simple as the salt in the water — fry being freshwater and larvae being marine.

A Working Definition

In its most classic definition, larva refers to a singular organism (usually an insect or a fish) that must undergo a complete metamorphosis before assuming adult morphology and behavior. Larvae is plural and used to define more than one of the same or different species.

Fry is generally a term used in the aquaculture industry to define the production of "seed" for commercial market. So, a larva could be a fry, but a fry doesn’t necessarily have to be a larva. A fry could be saltwater and a larva could be marine. Got it?

The life history of fishes is surely complex and full of exceptions, but the most widely accepted definition of larva is a newly hatched fish (freshwater or salt) that is adapted to life in the open water before settling or recruiting to the adult habitat and life style.

This is pretty simple in marine systems. Pelagic eggs are released directly into the water column or pelagic larvae hatch from demersal eggs and enter the big blue. Here, they develop away from the benthic structures of rocks or reefs for a period of weeks before metamorphosing into the juvenile form that adopts a demersal life style.

Freshwater Metamorphosis?

We often do not use the term metamorphosis when defining the early life cycle of freshwater fishes. Newly hatched freshwater fishes are typically much larger than marine species and generally do not undergo such drastic developmental pathways. On close inspection though, newly hatched forms of most freshwater species look markedly different from the juvenile or adult forms. If we look at the photograph of the Gold Gourami, it certainly doesn’t look like the adult.  I assumed that it warranted the term larva.

Every aquarist, fish farmer and fish biologist uses lingo to define certain developmental stages. Some of these terms are more widely accepted than others. To my mind, the term larvae is simple and somewhat all encompassing of the early life stages of fish, freshwater and marine.

Many have adopted sub categories such as prolarvae to define the stage of pelagic spawning fishes after hatching, but before first feeding. Some use this term, while others refer to this stage simply as early larvae.

Another difficult definition comes after metamorphosis, but before settlement. Most fish biologists refer to these as settlement stage larvae, but others call them pelagic juveniles.

For those who study and breed fishes, it is another world, full of wonder and, yes, confusion.

The Microscopic Gourami

Gold Gourami (Trichogaster trichopterus) larva with globular "water wings."

I know, I know, gouramis are freshwater fish, but I couldn’t resist snapping a photo to illustrate the beauty of design in form and function.

Anabantoids hold a special place in my book of fishes as they were one of the first aquarium groups to test my breeding skills long ago in a re-modeled closet fish room in my parents' home. (Anabantoids are the so-called labyrinth fishes that breathe air and include bettas, gouramis, paradise fish, and others.)

A few days ago when Dr. Jon Shenker’s aquaculture class at Florida Institute of Technology got a successful hatch of Gold Gouramis (Trichgaster trichopterus), curiosity got the better of me, and I grabbed a few for the microscope.

It is not hard to observe the many wonders of evolution that have helped shaped the form of adult fishes. Examples of intricate detail in construction are everywhere. Diverse body forms, fin structure, mouth parts and other characters allow nearly 30,000 different species of fish to thrive in aquatic environments.

Fusiform bodies allow swift and powerful locomotion in a fluid environment, cone-shaped buccal cavities accompanied by small mouths allow a rapid burst of negative pressure for suction feeding in deep crevices, and laterally compressed bodies facilitate maneuverability in tight coral grottos.

These are only a handful of examples that are easily observed in adult fishes. Casual observations that reveal diversity are easy to find in adult fishes; they are large enough to see without a magnifying glass, we can dive on a coral reef and observe them and we can keep them in aquariums to watch them.

Larval Marvels

Larval fish are different. Though they are magnificent and diverse in their own right, they are very difficult to observe without a microscope or some severe eye squinting. You typically don’t hear conversations among aquarists about how pretty a larval fish is or: “Hey, did you see the dorsal finfold on that snapper!”

That is why I love them. It is like a hidden world of detailed beauty. Every time I stare into a microscope I find something new and powerful that inspires a million questions. This is what happened with the gouramis.

The life history of common anabantoids is an amazing example of evolution. The labyrinth organ, unique to the group, allows gouramis and bettas to thrive in hypoxic (low oxygen) conditions that would be intolerable to most fishes. The labyrinth organ has been so successful in this group that the gills alone are insufficient to supply sufficient oxygen uptake. Gulping atmospheric air in mud puddles and rice paddies, devoid of appreciable levels of oxygen, is an incredible adaptation to living in stagnant waters.

Anabantoid Survival Tricks

But, how in the world does a fish reproduce under these conditions? How are the larvae able to survive when they do not possess a labyrinth organ and their gills filaments haven’t developed yet? Building a nest of mucus covered bubbles and sticking the eggs close to the surface is just the first step. By keeping the eggs near the surface, suspended in a raft of bubbles, the fish are able to tend the eggs in or near the surface film where the most oxygen would be.

But, what about the larvae? I had never seen a gourami under the microscope before. Though I have raised them on numerous occasions I never looked close enough to see what was "aiding" the larvae to survive under such harsh conditions. When viewed from above it looks like the larvae have "water wings," you know, those fluorescent orange inflatable arm bands that keeps kids at the top at the pool.

Two large dorsal sacs are present on each side of the body that keep them floating at the surface film. (At first I thought they were filled with air, but a bit of research suggests they contain oil remaining from the yolk sac. )Here, under the surface film, cutaneous gas exchange occurs to supply vital oxygen to a tiny fish without gills and without a labyrinth organ.  Pretty darn cool.

I am sure this is a known phenomenon in the anabantoid world and should be a well-recognized adaptation in the larval world, but for me, this is something new and helps illustrate our curious world.

Spotted Mandarins Graduate to Nano-Reef

It has been a little over three months since I stocked my first spawn of Spotted Mandarin (Synchiropus picturatus) eggs into a barren rearing tank.

Forty days after hatching they looked like mandarins, but were still far from revealing the adult colors so appealing of the species. I brought a handful of the juveniles to show off at MACNA (the Marine Aquarium Conference of North America in Atlanta) since they were starting to reveal some intricate patterns and bold colors, but they were a bit too small for most observers to find and appreciate.

When I got back to my lab, I grabbed a small net full of the mint-green juveniles and snapped a few photos. Instead of putting them back into the rearing tank, however, I decided to take them home to a nano tank and see if I could coax them into eating prepared foods. The nano tank is home to a few juvenile green mandarins fully trained to accept a 'mush' of prepared foods.

Within minutes, the little spotteds became active explorers and began pecking at the substrate. Over the next few days the juveniles began accepting prepared foods with vigor. My growing tank of captive-bred mandarins remains peaceful, easily fed, and becomes more colorful each day. It's quite amazing, considering that just a few months ago I was firmly convinced that mandarinfishes were poor candidates for the aquarium life, let alone captive breeding.

Boycotting the Wild Banggai Cardinalfish

Captive-bred Banggai Cardinals.

Profit, ethics and the marine aquarium trade

This year's Marine Aquarium Conference of North America (MACNA) heard a rather alarming call for action and a warning question issued to everyone involved in the marine aquarium hobby. At what price do we sacrifice conservation?

Working with MASNA, Eric Borneman introduced a grass roots effort to conserve the Banggai Cardinalfish, which he believes could face extinction in the wild within the next 10 years. In essence, Eric called for concerned aquarists and livestock sellers to boycott wild-caught Banggais and to support the trade in captive-bred Pterapogon kauderni.

Extinction Repercussions
The gist of the message is simple. In the absence of government protection (from our own as well the Indonesian country of origin), the threat to wild Banggai populations is real. Unlike most reef fishes, the Banggai Cardinal has a limited range in the wild, with just several dozen local populations enar small Indonesian islands.

Two local populations have already been wiped out, and if current collection trends continue we could quite possibly witness the extinction of more wild Banggai populations within a short time.

As I pondered the thought of extinction I questioned the responsibility of the trade. Can the aquarium trade afford to be responsible for causing the extinction of a marine fish species? The answer is and emphatic "No."

For decades non-government agencies, industry leaders, and aquarists have struggled to combat attacks (for example, ‘raiders of the reef’ in Audubon Magazine), to work against blanket collection bans, and illustrate that the hobby is sustainable and beneficial to conservation and education.

Cheap Fish, Poor Survival
This is where it gets confusing. The mortality rate of wild Banggais is horrible. It is not uncommon to lose entire shipments of wild fish, and the ones that survive long enough to sell seem to last only weeks. The reason is still a bit unclear, but crowding, stress and holding conditions are the primary concerns. Banggai Cardinals are imported in huge batches, and their immune systems are likely overrun by disease, possibly a newly identified virus.

So, wild fish are dying, which gives the fish a bad name in the eyes of hobbyists and wild populations are suffering. Hmmm. The confusing part comes when we look to the people breeding Banggais. They can’t compete with wild imports, as the market price is in the $3 US range. Banggai breeders are typically overstocked with healthy, hardy fish that can’t compete in a market looking for the lowest possible price.

Wild Banggais make a lot of people money along the supply chain, and their importation is not likely to cease until consumer demand for these fish drops. No one wants a sick fish and those that are sold (knowingly or unknowingly) breed aggravation among hobbyists. Dying fish are a major reason newcomers drop from the hobby.

When Banggais were first collected for the trade they fetched a king's ransom that was gladly paid. As the price dropped, so it seems did the quality. As in most aspects of the trade we have choices. We can choose healthy, captive-bred Banggais or wild Banggais that are likely to perish and contribute to the demise of wild populations as well as permanent damage to the image of the aquarium hobby.

Banggai breeders are becoming more prevalent throughout the country and there is no reason retail outlets should need or request wild imports. In my view, it is extremely important for hobbyists and local store owners to support local growers. A few extra bucks is a small price to pay to keep the breeders in the game and the Banggai Cardinal off the extinction list.

A Breeders' Dilemma
This is important. If a local breeder produces Banggais to battle extinction but can’t sell his or her stock because retailers want cheap fish, what is the answer?

Do we breed only the species that fetch a high sum in the marketplace at the risk of the species conservation status? Do we target rare fish to increase our profit margin? And do we avoid species like Banggais and mandarins because we can’t make enough money doing it?

These are certainly tough questions and the answers ultimately lie in the hands of the many that try. If we target rare fish we may make some money, but we may also increase the demand in the trade and possibly put more pressure on wild populations.

For years, the Splendid Dottyback was elusive and rare and everyone that observed the rare underwater photographs drooled over the possibility of obtaining one. Before long, they were available through commercial aquaculture sources. This spiked the specie's attraction, and wild imports increased exponentially. Collectors, wholesalers, importers—there is always someone waiting to take advantage of a popularity boost.

Whether we like it or not we have responsibilities. As hobbyists we have the responsibility to ensure a sustainable future for wild populations of the fish we keep as well as the hobby itself.

We need to identify species of concern and buy captive bred. As breeders we have the responsibility of propagating and learning as much as we can to preserve species of concern and offer sustainable alternatives. Personally, I love to raise a rare and elusive fish, but in the eyes of conservation suggest we concentrate our efforts on those that need it most instead of putting more pressure on wild stocks.

In the absence of a governing body, the multiple segments of the aquarium trade (exporters, importers, retailers, and consumers) are responsible for its future. Before the government becomes the body of involvement, let us join forces and demonstrate our passion.

References

Marine Aquarium Societies of North America
MASNA

Marine Ornamental Fish & Invert Breeders
MOFIB

Manual for the production of the Banggai Cardinalfish, Pterapogon kauderni:
Hawaii Seagrant Program, Clyde Tamaru

Banggai Breeding I by Frank Marini.

The Complete Illustrated Breeder's Guide to Marine Aquarium Fishes, Matthew L. Wittenrich

When do Spotted Mandarins Get Their Spots?

A group of juvenile spotted mandarins near 40 days after hatching.  The juveniles are quite active in their search for food and wrestle amongst each other to secure 'feeding zones' on the bottom.

Over the past several months I have learned a great deal about the behaviors and breeding of mandarinfishes (Synchiropus spp.), also known as dragonets. Mostly, I have learned that I want to know more.

Each new day brings a new challenge, a new question and more insight into the secret world of these fascinating fishes.

My first spawn of Spotted Mandarins (Synchiropus picturatus) are now around 40 days old and growing quite nicely. From afar they seem similar to the Green Mandarins at the same age. They are mostly a mottled tan color with an intricate pattern of dark browns and blacks. When the light hits their eyes just right they glow fluorescent green, giving the somber background color a bit more flair.

The head of juvenile Spotted Mandarins are more pointed and streamlined than the round and blunt heads of greens and when you look closely they just look mad. In fact, when you stare at the bottom of the tank long enough, juvenile spotteds are a handful and can be very rowdy fishes. They are constantly chasing each other around and perform combat circles quite frequently. No harm ever comes from these squabbles, but it goes to show that these little ones certainly take their feeding territory seriously.

When I first stocked the eggs into the rearing tank I counted the eggs volumetrically and estimated I started with roughly 80 eggs. Once again, similar to the Green Mandarins, I ended up with a surplus. A few days ago I counted 128 Spotted Mandarin juveniles hopping on the bottom of the rearing tank. I am very excited about this batch of captive mandarins and am crossing my fingers that they turn mint green with bright orange bullseyes soon. I haven’t attempted to wean this batch to prepared foods yet as I am hoping they will color up faster with copepods and enriched Artemia. My goal of creating an intricate collage of captive-breds of both species is ever closer.

See also: Breeding the Spotted Mandarin

Mutant Clownfish: A New Fish for the Nemo Set?

The other day I was visiting a local Florida fish shop and came across these Percula Clownfish. They had been captive-raised by a local aquarist and brought to the fish shop with great pride.

As I watched them writhe in a tight group amidst a fake turquoise coral, I started to wonder if there was room in the hobby for such aberrant or mutant fish. After all, Picasso Clowns, Onyx Clowns, and so-called Naked Clowns have all earned a place in the hobby. Would a fish with a contorted, doll-like head or missing vertebrae make a good pet if it somehow looked different from all the rest?

Culling Thoughts

I have always been a big advocate of culling. Any offspring with obvious morphological deformations such as missing gill covers, twisted vertebrae, smushed mouths and disfigured heads were to be destroyed.

The future of captive raised marine aquarium fishes in the industry is quite dependant on producing high quality offspring exhibiting every characteristic that makes the species desirable- or at least I thought. In the early days of captive breeding clownfish often looked like bull dogs and deformities were common. Colors were bland and it was hard for fledgling companies to compete against wild caught fish.

Over the years, however, we have learned significantly that nutrition and water quality can lead to a superior product that is healthier and infinitely more marketable than wild-caught specimens. If deformed fish begin to enter the marketplace more frequently will it affect the good name and future sale of captive raised fish or will it actually become a more desirable product?

Consumers Vote

As I pondered these questions I went back to the fish shop to take another look and every single one was sold to a new home. In the tank directly next to the mutant fish were normal looking Ocellaris Clownfish with no deformities and three perfect stripes.

Sadly, to me at least, it seemed these may have been too common, maybe even boring, as every one was still there bobbing up and down begging for a home. We have seen deformities become highly marketable in the freshwater aquarium trade. It is inevitable that they will invade the marine hobby?

Metamorphosis Happens: A Mandarinfish Work in Progress

Spotted Mandarin larva at 8 days.

Today, for about the 400th time this week, I re-read Wolfgang Mai’s article in Coral Magazine entitled Mission Accomplished: Spawning the Spotted Mandarin.

No matter how many species of fish we raise, there is always a sense of wonder and excitement when working with something new. For me, each new day is terribly exciting as I creep close to the larval tanks and hold my breath, hoping to find a tank full of healthy and active larvae instead of a scene of disappointment.

When successful reports exist, such as Mai’s, I tend to read the report over and over for reinforcement. When experimenting with breeding marine fishes, the anticipation and excitement grows while waiting to see the tiny larvae grow into something that resembles the adult form.

The first feeding larvae of the Spotted Mandarin slightly resemble those of the Green Mandarin, being bright yellow and tiny. Five days after hatching the Spotted Mandarins took a bit of turn from what I considered typical Green Mandarin development. Instead of turning bright orange they turned to the color of rust, or maybe dirty orange, with white spots on the dorsal and ventral finfold. An interesting aspect of development in both species is the total lack of pigmentation on the posterior finfold.

In the pictures, it looks as though someone has drawn a straight vertical line down the middle of the fish, but in fact a clear notochord and tail are present behind this line. Mandarin larvae are unlike most other reef fish larvae in that they aren’t too active in their search for prey. Often, after watching a group for hours I am amazed they can catch anything to eat.

At 5 days old the larvae became a bit more active in their hunt for prey and curled up in the classic "S-strike pattern" and pounced forward onto rotifers and copepod nauplii. A few days later the larvae thickened and still, appeared dirty orange or mottled yellow, never taking the bright orange color of the greens at the same age.

Eight days after hatching the larvae appeared almost awkward while swimming in the water column. Their body mass seemed to affect their swimming and they would curl their bodies wildly using them almost like sails to maneuver through the water.  I pulled a single larva from the tank to snap this photo. Pelvic fins were present, which means settlement isn’t that far away. Pectoral fins were present, but without fin rays. The notochord was still straight and the solid line separating the color from the clear seemed to stretch back a bit.

The larva seemed chunky so I imagine they are getting plenty of food. More to come…

See: Breeding the Spotted Mandarin with time-sequence images.

Coolest Fish in the House

After a 14-year hiatus of keeping mandarins, I must admit, they are slowly creeping up on my list of favorite fish.

Having met success in rearing large hatches of the Green Mandarin, Synchiropus splendidus, I decided to try the Spotted Mandarin, Synchiropus picturatus.

My motivation is being driven partly by photography; I have a vision. You know the images of dozens of Tridacna clams in different colors and sizes, squished together with their mantles touching? Yep, I want a picture of mandarins; Greens and Spotteds, all captive-raised and squished together to form a puzzle your grandfather couldn’t figure out. A picture that says “Wow”. 

Coolest Fish in the House

But, as always, a vision is far from the final product, so I thought I would share a bit of my struggle to get the image. It hasn’t happened yet, but I am hopeful and continue to snap some shots along the way.

Though somewhat similar to the Greens, Spotteds offer something entirely different. At first, it is the color and psychedelic pattern of this fish that commands attention. Mint green with orange bullseyes, a striking fish for sure. But, after a time, it is their personality that shines through and earns them a spot on the list of family favorites. Both species of mandarins are undeniably popular in the aquarium trade, but recently, my Spotteds hold the rank of coolest fish in the house.

The spotted mandarins sleep together, perched in the same rock, every night. They forage the tank side by side and are quite active in hunting frozen foods from the water column. Spotteds seem a bit easier to train to frozen fare and often take frozen mysids straight out of the pet shop.

Sure, weaning is sometimes necessary and the "Matt Pedersen, Put Them in a Breeder Box and Feed Them Live ''Artemia'' Until They Take Frozen Trick" works wonders. (See: Breeding the Green Mandarin.)

Broodstock Struggles

Three-day-old Spotted Mandarin larva. See full sequence of images to date.

I am bit embarrassed, more for my pocketbook than anything, but I have spent a small fortune on obtaining a few healthy pairs of spotted mandarins. Potential broodstock choices are always limited at local fish shops and most mandarins available are emaciated.

The degree of emaciation varies widely, but most are hurting for sure. I was successful in bringing a few really skinny females back to good health using live mysids to boost them up quickly, but lost quite a few that just couldn’t seem to get their energy back.

My favorite pair of Spotted Mandarins was given to me by two ambitious undergrad students at Florida Tech. Tim Morrissey and Ian Macdonald have formed quite a few pairs of spawning fish, including Marine Bettas, and left them in my care over the summer.

I took the pair of Spotted Mandarins home to a 28-gallon tank, fed them well and left them alone. Within a month they started rising together in a spawning spiral under the actinic lights.

The first spawn was very small, maybe 50 or so eggs. I collected them in a small cup and brought them to the lab to incubate and try my hand at rearing. Well, I accidentally spilled the cup and most of the eggs onto the floor. I dumped the remaining 3 eggs into a tank full of Green Mandarins and thought it would a neat surprise if they hit metamorphosis.

A few days ago, they spawned again. This time, I made sure not to spill them and was able to capture the process of eggs developing, hatching, and the larvae developing. It's one small step among many to bring a tank full through. More to come....

More Photographs Here
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See also: Breeding the Green Mandarin