The food or the environment

The food or the environment

Postby Luis A M » Sun Aug 19, 2007 4:57 pm

When we were considering the convenience of opening this forum,I stated ( I cant find it,our site is too large now) that FW fish could be easy to very difficult to breed,but easy to raise,while marine species are usually easy to breed but very difficult to raise.
This "FW aproach" makes most newcomers asking how some fish should be sexed,or paired or spawned,without much concern about the next step,raising the larvae,which is unfortunately the obstacle against which most of our breeding dreams crash.
I also said that for a rational aproach to solve this problem,in every case,when things go wrong with our larvae,we must ask ourselves the golden question."IS IT THE FOOD,OR IS IT THE ENVIRONMENT?",being the "environment" everything else other than the food.
I bring it back here because Witt´s book brings new ideas and I find it convenient to discuss them in the framework of this basic question.
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Postby mpedersen » Sun Aug 19, 2007 5:37 pm

Um, I have to say first foods. All other things are secondary..you can have everything else perfect but if there's no proper food, you'll still not have success. Conversely, we've discovered things like the fact elevated levels of ammonia and nitrite need not be the big issues we might have initially thought them to be. Witt's book make some key suggestions based on things we already knew, + expands on some of these basic concepts. I.e. the use of dark walled containers as larviculture vessels. The fact that size leads to stability.

Of course, again, if I don't have anything for the babies to eat, does any of that really matter?

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Postby Witt » Sun Aug 19, 2007 6:14 pm

Ahh, the perpetual question in closed systems and certainly a difficult one to identify with such a small organism. If larval fishes were as large as a thumbnail we could more easily identify symptoms leading one way or the other. I believe the most basic plan is to supply a rearing environment conducive to feeding. Without supplying proper lighting, background color, circulation patterns and a host of other environmental parameters we are just beginning to understand we are limiting the performance of our larvae. Case in point- dottybacks, clownfish and a few species of gobies can be raised in VERY small containers. Some time ago we ran some tests in 150 mL beakers, 3 L bowls, and 60 L cylindrical tanks. All tanks received the same prey at the same density. Larvae in the large tanks consumed nearly 3x the food they did in the small tanks. Survival as you can imagine followed a similar pattern. Sergeant majors raised in small tanks with all the copepod nauplii they could ever want died after 9 days. I am working with snook larvae now and they too, will not feed sufficiently in small tanks, dark tanks, tanks with poor circulation, tanks with a high waste load from rotifer cultures, etc. etc etc. I think the key is to think of food and the environment in parallel. Food is important, but without the proper environmental conditions larvae fail to feed properly and without proper food there is nothing in the environment that can save them.
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Postby Luis A M » Sun Aug 19, 2007 8:26 pm

Great to have both Matts chime in :D
Let´s the brainstorming begin...
Food or envir.?Both are critic,of course,but sometimes one leans to one side ,then to the other,because human minds are not computers and can´t deal with multiple variables simultaneously :D
But you blame the food when:
a- you suspect that larvae are not eating the offered item,and die at about the same time than starved controls,or when the yolk sac was gone.
b- when you think they are feeding,but they show little growth and less energy,especially when compared with other better item tried previously.
And you blame the envir.when larvae seem to eat and grow well but then die.
Of course there are cross links,under very bad envir.conditions,larvae won´t feed even if given the right food.
FOOD
So it seems many species don´t take rotifers,and if they do,they don´t grow well on them,on any of the different enriching aproaches.
What alternatives do we have?.Let see:
Wild plankton.That´s the best bet,but not a thing most of us can do.
Cultured calanoid naups.Sounds the right way,though still tricky to do in the required amounts.
What other alternatives?
Ciliates.Mentioned many times but with few actual results.Tintinids could be promising though.
Bivalve trocho.larvae.A company sell cryopreserved oyster trochos,I linked to an article somewhere.They said they were terrific with many food fish larvae but not with damsels.And it is too high-tech/expensive for a hobbyist.
But can´t we spawn and use foodmarket oysters,clams and mussels?.It seems it is not too difficult...
And couldn´t FW larval live food work?.Micro worms and vinegar "eels" can be raised in higher salinity and in HUFA enriched media,but will they be taken?
And inert food?.One sees bs eggs inside (larger)fish larvae.Very small FW larvae can be started in a suspension of egg yolk.And French researchers developed a food which worked as a starter larval food for some aquaculture fish.I tried both alternatives without success...
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Postby Luis A M » Sun Aug 19, 2007 10:26 pm

And ENVIRONMENT
There are lots and lots of envir.factors,but some could perhaps have been exaggerated,others misunderstood and finally others did not receive enough attention.Let me point at some few of them.
Green water technique and big tanks.Both are said to be very important in larval raising and both lack clear scientific explanations of how they work.And yet they work,as most of the people found.
Large tanks are particularly an annoying proposition to most hobbyists who can not even consider them,as happens with wild plankton.One reads frequently in aquaculture papers that eggs or larvae of some fish were put in a 50 cubic meters tank for rearing.One would like to think that out of the wall collision chances,there is nothing advantageous in housing the same larvae/L density in a big or small tank.
And WQ.Being larvae considered so delicate,I was surprised to see how high levels of NH3,or oscillations of salinity,pH and temperature they endure without any effect.
Bacteriae.Organics laden water and it´s high bacterial population could be a very relevant factor we seldom consider.Offshore surface waters have a low bacterial count and it is easy to imagine that marine larvae have evolved without the inmunologycal weapons to resist them,as their FW counterparts.Bacterial supression was significative in many fish and crustacea rearing successes.Checking for bacteriae,particularly Vibrio,is something simple and could be a routine test for aquarists.Because larvae killed by bacteriae don´t show the typical bacterial disease signs of older fish.They just die,suddenly.
But the culture plates tell you that you have Vibrio and how many,not if they are harmless or one of the bad ones.And yet we could rule out the bacterial factor.A vibrio free environment is possible.Witt,you know some modern protocol to achieve that with for instance oxytetracycline?
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Postby "Umm, fish?" » Mon Aug 20, 2007 1:20 am

But can´t we spawn and use foodmarket oysters,clams and mussels?.It seems it is not too difficult...


But I do believe it takes lots of space (big troughs), which most of us probably don't have and lots of phyto. (Sounds like a fun process, though! :) )

I was just reading Moe's _Beginner to Breeder_ book and noticed that he said that Julian Sprung had raised mandarins on some copepod nauplii and "marine infusoria." Anyone have a clue what that could have been? Ciliates? Does anyone have a reference for where Sprung wrote it up?

Thanks!
Andy

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Postby Scott » Sun Nov 18, 2007 10:35 pm

How come this discussion died?????

I have nothing to add that would be constructive, but this idea sharing is exactly what we need to get past the difficult species. Expanding in success or failure of others will be key in solving these problems.

so....... bump!
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Re:

Postby Luis A M » Mon Nov 19, 2007 1:06 am

Scott wrote:How come this discussion died?????

I have nothing to add that would be constructive, but this idea sharing is exactly what we need to get past the difficult species. Expanding in success or failure of others will be key in solving these problems.

so....... bump!

Glad you bump it Scott.For some reason,none of the big fish here took the bait :lol:
Let´s try to keep the fire burning.I was trying to think what species can not be raised on rots and came to the unexpected conclussion that most of them can not. :shock:
So "contrario sensu" what MO fish larvae,other than clowns,can consistently be raised with rots?The list is surprisingly short and should include:
Gobiosoma-Elacatinus gobies.
Cryptocentrus gobies.
Blennies-many species.
Gramma
Opistognathus
Pseudochromis

Is it so?.What other species should we add (remove) from this list?
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Postby Clownfish75 » Mon Nov 19, 2007 3:11 am

Luis im not sure about gramma's, i put some effort into a second run about 2-3 months ago in a rectangular 2ftX1ftX1ft tank with black sides and a white bottom.

The grammas took well to rotifers but then moved to a well enriched artemia and ran out of puff to make it through metamorphosis. I think i did a fairly good job of enrichment and also of water quality, along with the use of higher flow and green water (live). Realisticially aside from trying different enrichments and the use of different green water algaes im running out of options but to move to environment. People like Edgar and Matt Witt say it can be done but you got me how they do it. I surpose the logical next step is to try the tank idea.

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Postby Luis A M » Mon Nov 19, 2007 10:02 am

So you think it is "the environment"?And that Gramma should be out of the list of fish that can "consistently"be raised on rots?.
There are several other species:Calloplesiops,Assesor,other gobies,etc but I don´t know about how "consistent" their raising is.For some reason they are not frequently or easily raised.Perhaps dotties would fall there,see Martin´s and other people experiences.
And G.okinawae,IME and given their tiny hatching size,I would swear that they can not take rots.But Ed could do it,same as dotties.
So somehow they are species where the "magic touch of a master" is required,very special enrichment...
Or was it "the environment"
:?
P.S.I forgot Iris´filefish,but did she mention what she fed them?
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Postby Witt » Mon Nov 19, 2007 10:34 am

Ahhh, it's good to see some more interest in this two sided dilemma. I like to give examples rather than an explanation so here are a few quick ones to hopefully stimulate some thinking. I can raise a few local species like striped blennies and skilletfish without enrichment and using only rotifers and Artemia with a > 50% survival rate. This same diet with damsels = 0. But what about dottybacks? If I raise orchids without commercial HUFAs, but use greenwater (paste) I can generally pull about 50 or so from a single clutch. If I use HUFA this number is easily doubled. BUT, this is where it gets interesting. A labmate of mine wanted to try neon dotties. The next time the pair spawned the male got greedy and started eating the egg mass. By the time she pulled it there were 7 eggs left. I told her it would be a waste of time to try, but she did anyway. Three larvae hatched and three survived to complete metamorphosis. Hmm. So if I raise striped blennies in an 18 L bucket I get ~20% survival, in a 60L tank >50%. Skilletfish = 0 survival in a bucket, ~10-20% in a 40 L tank and near 50 in a 60L round black tank. I could keep going, but the trend holds with almost all species. I think there is something to Matts comment about trying to raise everything produced rather than concentrating on a smaller number of individuals. Think about water quality. The way I see it there are 2 major bottlenecks. One at first feeding and one at or near metamorphosis. The one at metamorphosis is definitely influenced by the feeding history of first feeding through this period. Without proper enrichment throughout the WHOLE larval phase larvae run out of gumption to complete this physiologically taxing process. So in the end, in my head anyway, I complete the circular argument that both are equally and dependantly important.
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Postby Lady Baboon » Mon Nov 19, 2007 2:28 pm

According to Iris's overview post (sorry have not translated it yet, but I am working on it) the first foods for filefish are brachionus and copepods.

Hope that helps
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Re: The food or the environment

Postby neman » Tue Apr 14, 2009 6:24 am

MATT states the he uses black tubs for laral rearing .im just wondering what the reason for that i may have miss read somwhere but are they larvae easier to see in black tubs ? i currently have a 150litre round tub im going to use to try rearing mandarin fry
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Re: The food or the environment

Postby William » Tue Apr 14, 2009 11:43 am

No, larvae are harder to see in a black tub. Round black tubs are used because they create an environment more similar to the open ocean.
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Re: The food or the environment

Postby Zooid » Fri Apr 17, 2009 1:29 pm

Better flow dynamics. The larvae tend to stay in the water column better and less dead spots.
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Re: The food or the environment

Postby rein08 » Fri Jul 23, 2010 8:55 am

I could say the environment.
They need it to be clean always.
Think of that.
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Re: The food or the environment

Postby "Umm, fish?" » Fri Jul 23, 2010 7:13 pm

But a pristine environment with no food = 0 fish, every time. :)
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Re: The food or the environment

Postby downbydasea » Fri Dec 07, 2012 8:37 am

I know this is an old post but I am curious. In the last 2 yrs as the thought process changed very much on this topic.
IMO the question is like asking what is the most important organ in the human body......you still have to have them all to live.
When someone shares something of value with you, and you benefit from it, you have a moral obligation to share it with others.
Chinese Proverb
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Re: The food or the environment

Postby Hordeumvulgare » Sat Apr 16, 2016 6:58 am

To add something...

I have been collecting copepods from the wild, trawling a simple net made from pantyhose and garden pots along a beach. I normally get one or two larvae in the "catch". Out of curiosity I have been leaving them in some buckets/containers with copepods, but these tanks are also where waste goes, (protein skimmer waste, tank bottom cleaning water, so the water quality must be low by any standard). To my surprise all the larvae bar one has survived and prospered. The larvae are from multiple species, as yet I cant identify any of them, and they do metamorphosis, and are successful healthy juveniles. Right now I have two of the more recent larvae in a 5 L clear plastic bucket, which continually changes in salinity due to recent rainfall (its sitting outside obviously). To this I just add unwashed artemia from a large bucket where I throw any unused artemia . The artemia bucket sits in the sun and grows its own wild microalgae food, but I never clean it (ts been added to without water exchange for weeks). Added to this the temperature fluctuates, one larger tank (80 L) I measured will fluctuate 6 C in a day, I assume the smaller buckets could change by up to 8 C / day

Now to my point. These larvae all tend to be quite small when caught as I assume the larger ones can get away, i'm guesstimating they are around 6 mm +- 2 mm, maybe a week or two old. They are all treated to variable food concentrations and generally low water quality after this, sometimes without aeration. Sometimes I get few copepods with the trawls and thus low levels of food are available for the larvae. But they survive my "harsh" treatment. Overall this suggests that broodstock diet, early larval diet and or environmental exposure (first week before I catch them), is playing a huge role in conditioning the larvae at least into the juvenile phase. I havent tried, but I am sure that if i exposed captive bred larvae to these conditions i would get standard terrible results, perhaps 100 % mortality.

It is possible that by the time I get to the larvae in the wild, natural selection has brought me the strongest, but other than this, any comments?
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