Rearing Abudefduf; comparing those round black tanks

[Witt]

Every aquarist interested in marine fish propagation undertakes challenges and vexations that can prove dreadfully annoying; this can often last years. Here is a brief synopsis of my epic battle with Abudefduf saxatilis. I thought this might be a good one to post owing to the rearing tanks used and the frustrations encountered.

Each year, as the water temperature slowly rises from the cooling of winter I patiently polish the glass on my diving mask in anxious preparation for the sergeant major spawning season. Usually in late May brooding male sergeants can be seen a good distance away underwater, their bright blue nuptial colors being a dead give away as to the location of their nests. Once the nests are located I place 12" ceramic tiles in a variety of locations near the brooding males. Eventually, one of the males will give and spawn on the tile.

After placing a new tile in place of the old, the tile containing the spawn is transferred back to the lab, inverted and supplied with a steady stream of air. Collecting eggs and hatching larvae is non-problematic and I can usually get over 1,000 larvae from a single spawn. This is an egg shortly before hatching.

I first attempted to raise sergeants 3 years ago. I hatched the larvae in black laundry sinks, fed them rotifers and watched them die. At 5 days there was a massive mortality. I added some wild plankton to the mix and routinely brought them to day 15. There was still a big drop at day 5, but I still got some to day 15. Then, I tried raising some with live microalgae, some with paste, some without rotifers, and several different densities and sizes of plankton, and I was beginning to see progress. Numbers would slowly dwindle until there were 2 or 3 left in the tanks by day 17. Flexion was just barely initiated and I kept thinking I was going to raise at least 1. Then, the next day they would be dead. By the time I thought I was getting somewhere the spawning season would be over and I was out of eggs until the next year. Well, finally this year I have good news. It turns out this is one of the pickiest little fish I have come across. Earlier this year I set up a bunch of experiments in three systems to get a little closer to my goal. All of the tanks are round and black, but they are vastly different.

These are simple whiskey barrel liners from Lowes. Tanks are plumbed to a central system with UV, skimmer and Bio-tower. CONSTANT slow drip into the system. These tanks are roughly 24" in diameter and 18" deep (about 20 gal. volume).

This is a new system I just set up to get more replication out of my experiments. Personally, I think these tanks are limited to hardy larvae such as clowns, some gobies and blennies and a few dottybacks. They are the same volume as the whiskey barrel liners, but notice the shape. These are taller and narrower. About 16" diameter, 24" depth.

This is my personal favorite; two 50 gallon tanks connected to central system with external gated standpipes.

So here is the real quick run down. Everything in the tall, narrow tanks died at day 5 - 9 no matter what diet they were being fed. Greenwater had no effect on survival. Larvae in the whiskey barrel liners survived to metamorphosis, but experienced a large die off at 5 dph and around 15 - 17 dph. Larvae in the 50 gal. survived to metamorphosis, still experiencin g a noticeable die off at 5 - 9 and 15 - 17, but decent numbers pulling through. In the larger systems greenwater definitely reduced mortality. Paste or live, didn't matter.

Food is THE major constraint. I put hours into watching these little guys. Swimming in a soup of potential organisms and they want nothing to do with most of them. While they do consume rotifers, dinoflagellates and a bunch of other organisms they definitely do not survive on it. Copepods...they will hold out for, inspect everything around them, but unless it jerks, jostles or tries to escape they don't seem to be interested. I watched one larva for about 20 minutes the other day inspecting and casting aside roughly 50 potential meals before it came across a copepod. At the sight of the copepod, the larva stopped, curled up into an S pattern, but the copepod moved. The larva relaxed, repositioned and tried again. This went on for over 2 minutes. That larva tracked and stalked that copepod until he finally captured it.

With a good density of copepod nauplii growth is quick and flexion is achieved around day 15. metamorphosis is complete by day 20, usually.
Diet has extreme effects on growth and metamorphosis. In earlier trials no larvae hit flexion until day 17 and the tip was barely flexed up.


Rearing tank design and food..... I hope this helps some of you in your personal quests.

Matt Wittenrich

[KathyL]

Very interesting, would be good to see the pictures instead of the square ? boxes.....

[Witt]

OK, I got somethin'. If I open the thread in Mozilla Firefox I get the pics every time. Using Internet Explorer I get little red squares. Any ideas?

[Witt]

Sorry for the eye melting little squares. Pics should be up for good now.

["Umm, fish?"]

Damn.



I need a new microscope....

[FuEl]

Hats off to you Matt! I've always wished I could have rearing systems like that in my house. I'm sure the photos of the larval rearing systems are helping many others with regards to system design.

As fish larvae rely on visual cues to identify prey, the effective hunting depth is probably rather similar for all rearing vessels since the illumination seems similar for all treatments. In the narrow vessels, larvae might be limited to successful feeding in maybe the top 1/3 or 1/2 of the vessel? In contrast, rearing vessels with a larger surface area might exhibit less intraspecific competition for food resources by fish larvae and give better results? In the large vessel (the one on the right), illumination seems to be closer to the larvae. Perhaps this could have also favoured the larvae in the larger vessel?

[mpedersen]

Stunning thread...if I wasn't embroiled in trying to finalize my wedding reading I'd have more time to soak this up and comment further

The one thing I noticed, Witt, your comments about the tall & narrow might rule out my thought of using 5 gallon buckets as an inexpensive solution for the home breeder...hmm.

Matt

[KathyL]

OMG, the pictures are fabulous.

[Clownfish75]

Hi Matt W

Thats very interesting

The university hear, has/does rear Pomacentrus amboinensis, and they do it often and profusely.

I remember that they alwayss aid that survival was a bit of a hit and miss affair, I do remember that the most successful person was rearing in large 1.5m dia 1.5m deep black walled fiberglass tanks. With Live nano and wild caught plankton. amazing the similarities.

May i ask what is the aspect ratio of the wiskey barrel vs that of the fibreglass tank? Any other idea son the disparity?

Have you ever tried to culture or propagate copepods to influence survival? I surpose really thats the next step.

Christian

[Witt]

You all bring up fantastic ideas about rearing. This is key to larval rearing!
FuEl, your comments on lighting are spot on. I did forget to mention that. In the last pic of the 50 gallon tanks I placed a fluorescent strip RIGHT on top of the tank. This helped out with amazing results. Lighting is VERY important. The picture was taken a while ago, but right now the tank on the left is filled with thousands of sargassumfish to day 8. On day 9 in all the other tanks they died with only about 1% actually consuming prey. I will keep you posted if these ones live.

5 gallon buckets are used by at least 4 people that I know of to grow larvae. The problem is the size. Clownfish, dottybacks (at least one person has been successful) and a few hardy blennies have survived this. Otherwise, I feel their use is limited. Commercial facilities experience dramatic die offs in all but the largest tank. That is probably why JCU uses large ones. I can't imagine anyone would try raising foodfish in anything less than 250 gallon volumes. This could be part of the problem. Throw a million angelfish eggs in a 200 gallon tank and see what happens. Red Snapper, snook, cobia, flounder...if you try raising them in a small tank you get massive mortality before day 12. large tanks just seem to work.

In the tall and narrow tanks I am sure it has everything to do with water flow and surface to volume ratio. I tried some of these tanks on an up-welling system, but it yields the same result. My personal favorite rearing tanks for home culture are the whiskey barrel liners from Lowes or plastic utility sinks. The sinks come with legs so they can placed in a row, fitted with standpipes, and plumbed to a system. The inside should be painted black. I use black spray-paint. Don't laugh. Hard acrylic like Krylon in high gloss. Then, i paint over it with a high gloss acrylic clear coat (Krylon).

Cultured copepods are definitely the next step. I will actually be setting up a collaboration in a week or so to see if first-feeding sergeants will take a few cultured cops and what species they prefer.

[mpedersen]

Throw a million angelfish eggs in a 200 gallon tank and see what happens

Is a million angelfish eggs in a 200 gallon tank feasible? If so, 0.0002 gallons per egg? But what about throwing 600 angelfish eggs in a 5 gallon tank (closer to 0.008 gallons per egg)? What about only 100 eggs in a 10 gallon tank (0.1 gallons per egg). I guess the core question is what makes a larger tank any better than a smaller one? We all know the obvious reasons, i.e. slower fluctuations in water parameters, but is that the actual issue we're facing? Or is the reality that one might put 2000 eggs in a 200 gallon tank, which when scaled down would still be approximately 0.1 gallons per egg.

It seems when we deal with first foods like calanoid copepods, we tend to get hung up on the fact that we can't raise enough of them for the larvae we have. Maybe we're going about this from the wrong angle, i.e. trying to raise every last larvae that hatches? If perhaps instead we focused on smaller scale using only a portion of a spawn or hatch, we might have better results? So perhaps when my angelfish spawn 600 eggs, I should only try to rear 50 of the prolarvae? In larger tanks, and we're talking pelagic spawner larvae now, how many prolarvae might make it to the first feeding stage?

FWIW,

Matt

[Witt]

My million eggs in a barrel speech was aimed toward curious motivation. Commercial finfish hatcheries routinely stock upwards of 100 eggs / liter into larval rearing tanks. It sounds like a lot, but the goal is to combat mortality. With most pelagic spawners (at least the ones that have been raised) you can expect less than 1% to survive to metamorphosis. The panther grouper for example; millions of eggs are stocked into large concrete or earthen ponds. Hundreds make it, but out of how many...If we applied this same concept (large tanks and lots of larvae) like the commercial food fish guys use, how many species of ornamentals do you think we could rais?

If we kept going on the down scaling theme we could end up with one egg in a liter soda bottle or 5 eggs in a thermos. Feeding selectivity trials conducted in different size vessels suggest that feeding is largely influenced by larval tank design. As an example, larval orchid dottybacks feed reliably in 3 - liter black bowls. Comparing these results to those left in 20 gallon larval tanks show amazingly different results. Which one reflects the true feeding behaviour of the larvae? Again, if I see that larval sergeants are feeding in a 50 gallon tub, does that mean this is how they would behave in nature? The answer is probably no. Bottom line is that when we scale up the size of the rearing tank larvae behave differently, develop faster and survive longer. This is the case with the sergeants and I am still a long, long way away from achieving great, reliable success. Everything from hyrodynamic flow, contact with side walls, Reynolds numbers, surface to volume ratio, all the environmental parameters that saltwater can tease apart, illumination and food all influence how well a larval tank will work.

And Matt, you bring up a fantastic point. Often, we simply try to raise too many larvae. This is usually good with a species that will consume what we offer. There are bound to be mortalities. Stocking more, assuming our larval tanks and feed cultures can sustain them, assures we bring more through. BUT, when copepods are limited what do you do?

With the sergeants they are eating certain things from the plankton. I haven't opened too many up yet, but it looks like they prefer a copepod nauplii and metanauplii of a distinct calanoid. So I have run into a great many problems with this. First, everything else in the tank needs to be flushed. I have a constant drip from a central system, but my standpipe only has 150 micron mesh screen. So along with the fish larvae I am now growing shrimp, jellyfish, nudibranchs, barnacles, you name it. When I add more plankton to introduce the preferred prey I inevitably add more of the stuff they wont eat. So as the larval period goes on I get an increase in the density of the stuff they wont eat and a decrease in the ones they will.

Intraspecific competition is high in these larval tanks; they are all competing for a limited resource, that darn copepod. Mortality eventually weans the population down to a level that can be sustained by the amount of copepods I offer. Who knows what would have happened if I only started with one or two hundred larvae??

I brought back some more eggs today for another go. I will try things a little different this time around. Now that I kind of know what they are eating and what they are not, I set up another system with a fast turnover to flush all the other stuff out.

[FuEl]

Spot on! The crazy larval rearing syndrome whereby one tries to rear every single larvae.

[Peter Schmiedel]

Matt,

but what are according to you the main reasons for better results in bigger tanks?

I could assume:

1. More liter per larvae reduces water quality issues
2. More liter per larvae reduces impact of pheromone produced by the larvae
3: More liter means more phytoplankton and maybe more stabil water conditions
4. The already mentioned surface / hight ratio
5. Water movement improvement

BTW Really awesome pictures !!

[Luis A M]

Fascinating thread,Witt!(or Mark W.,whatever you like more)
And neat pics!Is that FIT?BTW,you met Andy R:there?
What are your plans,will you keep researching larval culture as a pro?

Every aquarist interested in marine fish propagation undertakes challenges and vexations that can prove dreadfully annoying; this can often last years. Here is a brief synopsis of my epic battle with Abudefduf saxatilis. I thought this might be a good one to post owing to the rearing tanks used and the frustrations encountered.

I feel very identified with this.Only that my battle with Chrysiptera lasted not three but thirty years!

Each year, as the water temperature slowly rises from the cooling of winter I patiently polish the glass on my diving mask in anxious preparation for the sergeant major spawning season. Usually in late May brooding male sergeants can be seen a good distance away underwater, their bright blue nuptial colors being a dead give away as to the location of their nests. Once the nests are located I place 12" ceramic tiles in a variety of locations near the brooding males. Eventually, one of the males will give and spawn on the tile.

After placing a new tile in place of the old, the tile containing the spawn is transferred back to the lab, inverted and supplied with a steady stream of air. Collecting eggs and hatching larvae is non-problematic and I can usually get over 1,000 larvae from a single spawn. This is an egg shortly before hatching.

Great aproach!Eco-friendly,and you avoid variables related to broodstock management.I think this is how Martin M.and Forrest Y.could raise the jewelfish,M.chrysurus,one of the few reports of damsel raising available.

I first attempted to raise sergeants 3 years ago. I hatched the larvae in black laundry sinks, fed them rotifers and watched them die. At 5 days there was a massive mortality. I added some wild plankton to the mix and routinely brought them to day 15. There was still a big drop at day 5, but I still got some to day 15. Then, I tried raising some with live microalgae, some with paste, some without rotifers, and several different densities and sizes of plankton, and I was beginning to see progress. Numbers would slowly dwindle until there were 2 or 3 left in the tanks by day 17. Flexion was just barely initiated and I kept thinking I was going to raise at least 1. Then, the next day they would be dead. By the time I thought I was getting somewhere the spawning season would be over and I was out of eggs until the next year. Well, finally this year I have good news. It turns out this is one of the pickiest little fish I have come across.
In the larger systems greenwater definitely reduced mortality. Paste or live, didn't matter.

I also crash against the 5th day barrier,and for years they´d never make it thru it.It must be nutritional,though my starving controls died sooner.

Food is THE major constraint. I put hours into watching these little guys. Swimming in a soup of potential organisms and they want nothing to do with most of them. While they do consume rotifers, dinoflagellates and a bunch of other organisms they definitely do not survive on it. Copepods...they will hold out for, inspect everything around them, but unless it jerks, jostles or tries to escape they don't seem to be interested. I watched one larva for about 20 minutes the other day inspecting and casting aside roughly 50 potential meals before it came across a copepod. At the sight of the copepod, the larva stopped, curled up into an S pattern, but the copepod moved. The larva relaxed, repositioned and tried again. This went on for over 2 minutes. That larva tracked and stalked that copepod until he finally captured it.

With a good density of copepod nauplii growth is quick and flexion is achieved around day 15. metamorphosis is complete by day 20, usually.
Diet has extreme effects on growth and metamorphosis. In earlier trials no larvae hit flexion until day 17 and the tip was barely flexed up.

I only once tried nauplii of two copepod species and results were not particularly good,but it was just once,and there are so many variables...

It seems damsels hatch in four different larval development stages,the less developed being Dascyllus,almost prolarval,with unpigmented eyes,then Chromis,Pomacentrus and Chrysiptera.
Where would A.saxatilis fit?.They look very well developed in your pics but they measure 2.2mm TL according to the scale?.C.taupou hatches at 3.19 mm TL.

The most frustrating part was that when some larvae passed the 5th day death toll,and began to grow well and take bbs,when they were ready to meta,around day 20,they died suddenly.The larger died,the smaller kept growing until they were ready...to die And they died in perfect health and nutritional conditions,suddenly,sometimes under my eyes.
Somehow I came to the conclusion that they died because they could not resist stress,being meta time a stressful time;and correlated this condition to being fed on bs.
So I tried to raise them "bs less" which was not particularly difficult,and for the first time I was presented with the wonderful blue glimpse of newly meta juvs.(getting poetic here:) )

So I agree about the copepod way and will try to explore it.But landlocked hobbyists have severe handicaps regarding volumes of ASW,algae and copepod mass culturing.But no challenge,no fun,right?8)

[Witt]

Luis,
You bring up some very interesting points about damsel culture. For some strange reason these little fish are extremely tough to raise. One would think that their nearly ubiquitous occupation in marine environments would bode well for captive propagation. Who knows.
The pics are of some larval systems I set up in a lab here at FIT. And yes, Andy Rhyne, an ambitious and enthusiastic young soul, I met here.

Sergeants hatch out small. 2.2 mm NL is about right for newly hatched larvae. The picture is actually of a 2dph specimen and the scale bar is average (I put it together quick so I could post it). I think its pretty accurate though. I worked with C. taupou last year before a fire killed every last broodstock. Sergeants, I believe are slightly larger at first feeding.

My goal with the sergeants was to obtain some data for my dissertation. I thought it would easy at first, but getting these data points has taken a dreadfully long time. Your notes on Artemia are interesting to me. I tried and tried, but these larvae will not touch, let alone stop to inspect an Artemia. Man are they picky. Artemia is well associated with shock and sudden death in larvae. It seems the fat content of the Artemia builds up in the soft tissue.

During the first year, the hurdle was the 5 day mark. The second year it was the 15 day mark. Still today, the 15 day mark is HUGE. They wont eat Artemia and feed on limited organisms in the plankton. I find that my only means of success is to keep the larval tank on a flow through system to constantly flush the plankton from the tank. This is important to get rid of what they wont eat. Then, I need to tow almost constantly to offer them what they will eat. It is interesting that my success also increased with 24 hour light. At night with the strip light right over the tank the copepods form a writhing mass underneith it. I have a strong upwelling flow and the larvae sit in the current and wait for the prey to pass by. They remain stationary and frantically turn their head from side to side searching for the "candy". When they find it they ride the current and attack the plankton beasts. One day Luis, we will find that answer.

[Luis A M]

Matt W.-Witt (choose the one you like more,your call )
It is a great mile stone that we found you and took out of the closet!
(The smiley means that I´m joking, some people don´t appreciate latin humor)
Seriously working together and exchanging experiences is the sure way to make this happen.And I refuse to accept the word "impossible"as related to larval raising.
I have lots of stuff to comment/discuss but I´ll work them out in the larv.forum as they´re general,basic,almost philosofical when the mood strikes me
As for damsels,after clowns and neon gobies,they were the sure candidates for commercial breeding,then in the 70´s when all began.And they never were done.Some say there was no real interest,as they´re so cheap.I think it could not be done because they´re so difficult.
But how difficult?.More than Gramma,or jawfish,or Pseudochromis?.

In closing,two "basic"questions:
Why many food fish can be raised and only few ornamentals?Is it because only "easy" species are chosen for aquaculture?(though snappers and groupers seem to require copepods).Or because of the methods employed?(large tanks/ponds,lots of turn over water)

And,do you believe a step by step aproach will take us better to the big prices?.Should we master clowns,then neon gobies,then whatever,each step at a time? Or is it OK to start by aiming to the elusive pelagic spawners?
This is somehow based on the premises that larviculture techniques should be the same for all planktonic larvae,only requiring different levels of perfection,i.e. if you can raise the "top of the hill",say Centropyge,you can raise everything else.Which might or might not be true.
Well,you see,the "mood"caught me and I slide out of the damsels...

[Witt]

Luis,

Damselfish have always been percieved as the 3 for $15 fish. The starter fish; those pretty blue fish you watch die when you seed your new system. Commercial growers tried with a few species in the early 90's, but never achieved great success. The goal was to produce domino's, blues, and green chromis in mass culture. Obviously, we know how tricky that can be now. I think growers never really took an interest because of their price. Read the reports from Moe and Hoff about how hard it was to get a good buck for clowns and even French Angelfish. How then, could researchers spend years going after a damselfish that would fetch no more than a few cents? More recently, growers are realizing the need for captive bred fishes, and this has led to new interest in damsel culture.

Which leads to your next point. Damselfish culture, in my opinion, far surpasses the difficulties associated with clownfish, jawfish and dottybacks, by far....

I beleive the reason more species of ornamentals have not been raised is a very simple one. NO ONE HAS TRIED>>>>Think about ten years ago when the list of captive bred fishes contained perhaps 20 or so species. Now, scan this forum....Proof in itself that when dedicated hobbyists set upon a goal it can be achieved. Food fishes have value, often backed by major financial support, and tremendous interest for research and development. Ornamental aquaculture is just starting to gain popularity in the world of financial grants.

I think it is good for culturists to gain experience with the principals of larval biology before tackling a 'difficult' species, but it is certainly a double edged sword. I think its good to know how things are commonly done, but perhaps more important to keep a curious eye on potential new ways to solve old problems. The hobby is set upon a platform of opinion. Keen eyed and mind boggling observations and approaches to rearing by hobbyists will almost certainly be the key to unlocking rearing mysteries.

[Witt]

As the aquarium hobby usually goes, space is limited and time is short. It seems there are never enough larval tanks for everything you want to accomplish and rarely enough time in the day to tend what you have set up. I needed some open tanks for various projects so I cleaned out the last of my sergeant major tanks and thought I would update my photo log for the species. From the last batch I pulled nearly 68 through. This is them at 35 dph.

And at nearly 70 dph

And the complete life cycle picture

My newfound interest in damsels has me eying Starck's damsels. Who knows...Hopefully that will be next years post.
Matt Wittenrich

[mpedersen]

Matt, with Luis's success with C. tapaou and the infinite marketability of this and others, C. starkii is already on my personal short-list for the 2008 Breeder's Challenge Species...I can tell you now I'd be in on that! We just have to convince Christian and put it to a vote

FWIW, I do know that Tropicorium has had a breeding pair in the past, and I have pictures of several "males" and 1 lone "female" saved from the Live Aquaria Diver's Den, so I presume that in addition to the obvious sequential hermaphrodism at play, there is actually well known, if not actually documented, dichromatism in C. starkii!

And BTW, I am floored with those Sergant Majors...NICELY DONE!

Matt

[Witt]

Thanks matt,

I must admit - I have stared at Starkii at local shops for years, but it was always in passing. Now, I think its on to purchasing. The bad thing about this challenge is obtaining the broodstock. At nearly 30 bucks ea. and the random approach to pairing it could take a few dollars and a little bit of luck. Protogyny is probable, but the large ones offered for sale are probably terminal. What have you seen regarding dichromatism? I am very interested.
If you are interested in this one, we should definitely give it a go.

[mpedersen]

Witt, I'm going to email you the picture. Sorry to take this thread on the tangent.

The description associated with that image was:

Female Starkii Damsel.
Size: 3/4"
121306120 Chrysiptera starcki $19.99

This is the ONLY "female" Starkii I've seen listed in the Diver's Den section. They have listed 7 "males" which are all what you traditionally think of as a Starkii damselfish...the "female" from LA.com was not as vibrant as a male, with yellow anal and ventral/pelvic fins (which are blue in "males").

FWIW,

Matt

[Luis A M]

Witt,great to hear from you again and the pics are just great!
Funny,I also stare at starkis and almost bought some a couple of times,but passed.I will get them AFTER I find how to raise decent numbers of taupous.
Will you be around?.I wanted to discuss some larviculture issues and needed your thoughts.
Why you guys think damsels are sequencial hermaphrodites?.I don´t

[Witt]

I agree with Luis in that I 'almost' bought them tons of times, but the price tag stopped me. This happens all the time. But, heck if Matt never picked up on my mention of C. starki it would still simply be on my list. Now, I have motivation. I started another thread and would love to see this one roll through to metamorphosis. Luis, I will be around. Matt thanks for the pic. I am very curious now.

[Iris]

Hello Witt,
how do you clean the ground in the Tanks? When the Larvae are very small you have a lot of fun?
And what ist with the food? when the water goes to the skimmer then to UVC and then to the larvae, the food are died? its that no Problem with the waterqualiti?
You give the food around the day?
Thanks