ID sharks theories?

[Chub_by]

Extreme example but makes the point. I see. It may not have been some kind of mysterious, biologically/chemically induced stunting

The fish release hormones into the water, which reduce growth. That's why fish in overstocked lakes also stay smaller, and fish in river are not stunted unless there is no food.
So when doing WC you remove hormones, thus allowing growth.


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[mindfuloffish]

The 11-year old ID shark I mentioned was kept on a variety of typical fish food such as NLS pellets and flake. He got regular water changes. He went from a 55 gallon to a 90 gal. to a 210 gal. in the first 10 years. I thought they lived about 20 years. Where can I find the info. that they live up to 50 years?

[Stavfish]

I have two ID Sharks in my 15,000 gallon outdoor setup. I got them about 10 months ago around 5 inches; previously living in a 55 gallon. They are now approximately 2 feet in length and are showing no signs of slowing down. The person I got them from purchased them from a non chain LFS. They eat algae and veggie wafers, shrimp, and pretty much everything else I put in the water intended for some of the other fish. They are showing no signs of slowing down anytime soon.


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[thebiggerthebetter]

You are wrong, all living species can experienced stunting conditions.

Thanks for the correction. I guess it'd be more proper to say different fish stunt to different degrees. As I said in that post I only know this things via hear-say.

[thebiggerthebetter]

The fish release hormones into the water, which reduce growth. That's why fish in overstocked lakes also stay smaller, and fish in river are not stunted unless there is no food.
So when doing WC you remove hormones, thus allowing growth.

Thanks for the schooling. Is that what that article say? I only knew of alpha-fishes releasing growth inhibiting hormone in the water that affects only their "school-mates" (which appeared understandable to me - it intends to hold to its size and supremacy), never knew that all release hormones that inhibt their own growth. Makes me wonder what's the purpose of this bodily function in nature...? My current deep ignorance tells me it is useless?

I am wondering if stunting and malnurishment/undernurishment in the light of the ongoing discussion are two unrelated things that may lead to similar results but biologically they are not related (I can't be sure for lack of knowledge). You differ? I mean a fish can be fed adequately but can't move much and get stunted.

[thebiggerthebetter]

The 11-year old ID shark I mentioned was kept on a variety of typical fish food such as NLS pellets and flake. He got regular water changes. He went from a 55 gallon to a 90 gal. to a 210 gal. in the first 10 years. I thought they lived about 20 years. Where can I find the info. that they live up to 50 years?

What I said was "These fish can be expected to live half a century." Unfortunately there is no source of their possible age known to me. I am sure professionals like Silurus on PlanetCatfish know. I simply read ichthyologists and high level keepers often sayng big cats should be able to reach 50 years of age. Too few keepers can accomplish such a fit of keeping a big cat for so long - pretty much for most of their own life. It is not easy or rather often impossible to determine the age of a wild-caught fish.

Two data points I know for sure are 1. our colleague Taksan has kept two RTCs for 27 years and 2. PinkButterfly's Synodontis euptera (not a big cat) has just turned 28 years (there are many other keepers reporting 25-28 year old syno euptera too).

Where is your expectation of 20-year lifespan coming from? I'd not disagree with it as it is more realistic, I think. But I also would rather not set goals for myself too low...

In fact 999 of 1000 fish of any kind die from accidents and our ignorance. I always remember the words of one of my teachers: "Do you know what the average life span of koi in the US?" And then he would answer: "Two weeks", while of course it is reported that koi are inherited in Japan from generation to generation and can live 90 years.

[mindfuloffish]

What I said was "These fish can be expected to live half a century." Unfortunately there is no source of their possible age known to me. I am sure professionals like Silurus on PlanetCatfish know. I simply read ichthyologists and high level keepers often sayng big cats should be able to reach 50 years of age. Too few keepers can accomplish such a fit of keeping a big cat for so long - pretty much for most of their own life. It is not easy or rather often impossible to determine the age of a wild-caught fish.

Two data points I know for sure are 1. our colleague Taksan has kept two RTCs for 27 years and 2. PinkButterfly's Synodontis euptera (not a big cat) has just turned 28 years (there are many other keepers reporting 25-28 year old syno euptera too).

Where is your expectation of 20-year lifespan coming from? I'd not disagree with it as it is more realistic, I think. But I also would rather not set goals for myself too low...

In fact 999 of 1000 fish of any kind die from accidents and our ignorance. I always remember the words of one of my teachers: "Do you know what the average life span of koi in the US?" And then he would answer: "Two weeks", while of course it is reported that koi are inherited in Japan from generation to generation and can live 90 years.

Thanks for the clarification. I was basing 20 years on the fact that's the number I've read most often. I've had plecos live 20 years. I also have my original koi that I obtained 16 years ago. I expect to have her the rest of my life. I'm really curious now to see how long my ID shark lives.

[Chub_by]

Thanks for the schooling. Is that what that article say? I only knew of alpha-fishes releasing growth inhibiting hormone in the water that affects only their "school-mates" (which appeared understandable to me - it intends to hold to its size and supremacy), never knew that all release hormones that inhibt their own growth. Makes me wonder what's the purpose of this bodily function in nature...? My current deep ignorance tells me it is useless?

I am wondering if stunting and malnurishment/undernurishment in the light of the ongoing discussion are two unrelated things that may lead to similar results but biologically they are not related (I can't be sure for lack of knowledge). You differ? I mean a fish can be fed adequately but can't move much and get stunted.

Well, it isn't good for a single fish; but the population of a species profits extremely of this! An example are two native german fish: Perch are very often stunted in smaller bodys of water. In fact, they often reach maturity at 4" and are maxed out at 5-6"!(This is a fish that has the potential to reach 1.5 feet)
But, in these waters, there is still an abundant perch population.
Pike do not tend to stunt like this. They often will reach full size in smaller waters with not much food; but then they start cannibalisation; the population of pike in the water suffers.

EDIT: I got you on the unrelated ways of stunting! I think that is very well possible,but I lack the scientific knowledge to know for sure.


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[necrocanis]

Hmm, this was an interesting read. I would like to add that I have owned an ID shark for 1.5 years now. I purchased him and another at 1.5" from walmart at the time. lol. Anyway they were housed in a 40 gal aquarium to start with and once they reached 5" in length I moved them into my 100 gal aquarium. There they have lived with a raphael, and two sun cats for the last year. One was killed by the sun cats the first night. It was the smaller and lower growing one. Trying to remember everything that was mentioned here I will say that the smaller one was darker in color, and the larger, more agile, and faster growing one was lighter colored. Since this event the larger one has grown from the 5" mark to just 9.5" in a year's time. That's about 7-8" in just 1.5 years time. The tank is over filtered, and I do water changes to the extreme as I always have for large catfish about every other day to twice a week on the light side. This guy has the biggest apetite of any fish I have kept. He even out eats the vulture catfish I just purchased. I had noted a few years ago that I thought I was keeping two seperate species of pangs. Thread here.

http://www.monsterfishkeepers.com/fo...atfish+bonanza

I was shot down about my theory of different species even with the heads of the two kinds I had being very different. I was told that one was probably wild caught and the other was captive bred when I checked with the experts. How no one but me and select few could see the differences is beyond me. The ones with a more blunt head definitely grew faster than the ones with a more elongated snout. Note that all these pangs were kept in a much smaller 30 gal aquarium the entire time I had them and they had lower filtration as well. They grew faster than my current ID shark. Just thought I would share my expirience. I use to clean a 125 gal tank that had two 2' ID sharks that were 25 years old. They were way under filtered, way underfed, and looked like death when I started, I changed the filtration and did water changes weekly. The fish actually started to grow again after they put their mass back on. They were fed flakes their entire lives up til when I started caring for them.

[necrocanis]

I can't remember as it's been years since I did the research but I remember reading about them being farmed in florida for the pet trade, and now I can go the local grocer and get the fillets of ID shark any time I want to.