Special Nutrients

[csababubbles]

There appear to be quite a few fish that have largely specialized in their diets. Many fish have sponges as their main diet, others eat mostly jellyfish, etc. For example, Moorish Idols stomach analysis shows a huge percentage as sponge, some large angels also eat mostly sponge or jellyfish.

My question is whether or not we can provide those same nutrients that are found in sponge without actually providing sponge or jellyfish. Do we know what specific nutrients are in sponges or jellyfish that are not available elsewhere on other foods? Or can they by substituted with other types of food that have very similar nutrient content.

On a side note, we all know there are some fish that don't acclimate well and survive in out aquariums, like the Moorish Idol. Is it because they are not acclimating well or is it because they are not getting the nutrients they need? I would assume it was because they were not acclimating well enough to captive care, and that we can substitute foods to get their nutritional needs met. But what throws a wrench into it is that many many Idols eat like pigs and live in nice, reduced stress environments with high water quality, but still die. What are they dying from then if its not nutritional? I mean, aside from aquarist mistakes like improper QT, broken heaters, etc.

 

[leebca]

Fish that are obligate eaters of certain marine lifeforms are the most challenging to maintain. In general, fishes like the Moorish Idol do have 'favorites' but do in fact (in the wild) eat other foods.

We know much about the general needs of marine fishes, but not of specific species (except for some food fishes). I've pulled together what is generally known, in my post about nutrition.

In the case of the Idol, there is something lacking in their diets. In the wild and in some captive environments I see the tall fin trail out several inches and remain stiff or firm to the very tip. Most home aquarium fishes don't. Their streamer ends the last inch or less into a flapping fin -- not stiff. There is something that is missing or something that is there that shouldn't be there. What it is, I can't say.

This will be the case for some fishes which don't have a means to display there is something amiss.

Most die early from stress. Most of those are space stressors coupled with the nourishment stressor(s) -- assuming it has appropriate tank mates. Or maybe it has more to do with water quality?

I note one thing of maybe little importance -- the captive fish maintained in sea water rarely have the limp end to their streamers. Those in artificial water usually have this after a few months in captivity. Maybe there is a factor of something missing or something in the artificial water? We know that artificial salts mimic the sea, but there are ingredients in higher or lower quantities because of the choice of the quality of the salts used. Most are considered innocuous but. . .are they really? Something is happening that is beyond my knowledge.