Fish nutrition and diet variation

Renegade Aquatics

Polypterus
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So this came about due to a thread I was reading earlier https://www.monsterfishkeepers.com/...-baby-piraiba-with-live-small-shrimps.726434/ and the topic of nutrition came up. It came up that shrimp shouldn't be staple due to its lack in vitamins, so I decided to message thebiggerthebetter thebiggerthebetter on the matter since I didn't wanna derail that thread. After a few messages he suggested I make a thread, my question is what is the best frozen foods you can feed to your fish ranging from (6-12in.)
Here was our messages
TBTB: Shrimp is high in thiaminase and generally shouldn't account for more than 10%-20% of the diet, unless one specifically makes sure their fish is getting enough vitamin B1 or the fish is a specialist in crustaceans. Shrimp and tilapia filet are poor in supplying crucial nutrients and are usually just good protein sources. Even wholesome feed such as whole frozen fish do not appear to be a foolproof feed for our pet predators. So the two safer bets are to get a fish to also take an all-in-one pellet and/or soak the feed in Vita-Chem. I do both. With smaller fish it is easier to vary the diet as many smaller feeds are available, both dry, frozen, and fresh. With large fish varying a diet like that becomes impossible so many even resort to making their own feed as the commercially available choices are 100x narrower than with small fish.

RA:Hm, alrighty I understand, since I'd personally I'd prefer to feed frozen, what frozen foods would you recommend? she's about 12cm now and will probably top at 25-30cm. I would also like to thank you for the detailed response, I appreciate it greatly.

TBTB: I buy whole frozen fish from bait wholesalers (small, 2"-6", from Bionic Bait of Pompano Beach, FL and arger, 6"-24" from Aylesworth's Fish and Bait of Tampa, FL) or people can find them at retail bait shops. The best would be a whole fish that your catfish can swallow, or it can be cut into appropriate size pieces. I buy frozen marine bait fish. I am not sure f/w can be found, I've never tried to search for it and never came across an offering, except larger fish in the 1'+ range such as gizzard shad.

I have come to the realization that whole frozen marine fish diet may not be a good long term diet and may eventually lead to some nutritional deficiencies. Hence for those of our fish that take only that frozen-thawed diet I either stuff pellets inside or pour VitaChem over them and soak.
 

thebiggerthebetter

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I too am looking to learn from what others have to say on the subject.

My statement that the diet of (almost) exclusively thawed whole marine fish can still lead to apparent nutritional deficiencies is based on several cases of losses of our fish where this is the only or one of a few possible explanations. Such losses included

-- 4x apurensis catfish 1.5'-2', after about 2-3 years on such diet,
-- 2x gulper catfish, ~8", after 3 years,
- 3x orinoco and 2x azul pbass, 1.5'-2', after 4 years,
- 1x barramundi perch, 3'+, after 4 years

... off the top of my head.
 
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thebiggerthebetter

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Anyone out there with a similar or dissimilar experience?

Anyone with a grounded opinion?

Nutrition aficionados?

Experts?

SOS for RD. RD. ? haha...
 
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Galantspeedz

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I am now feeding anchovies, about 3 inches in size

Delivered fresh to me and I repack on a per feeding basis and freeze it

I do not gut or remove any part of the fish before feeding

Not sure about the vitamins components though
 
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RD.

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Viktor's astute observations are spot on. When in doubt, look at what the aquatic public zoos do when feeding frozen fish to their carnivorous species. They all supplement with vitamins - it is essential to the long term health of the fish.

I posted more on this subject in a past discussion.

Just a couple things I wanted to add. Although certain fish (and it's a very long list of fish species) such as smelt can sometimes have excessive amounts of thiaminase, the workaround to that is simple. Supplement B1 (thiamin) a few times a week. Problem solved. Boyd Vitachem is one such supplement. If one is primarily feeding frozen food from the supermarket then vitamin supplementation should already be part of the feeding regime. This is how public aquariums, zoos, etc, keep their frozen fed fish healthy long term - vitamins & trace minerals are not just a good idea, they are mandatory to anyone feeding these kinds of foods as the main portion of a fishes diet.

My advice when dealing with fresh fish products, buy fresh, freeze for 48 hrs at 0F (-18C) to destroy any potential parasites, and use up within 30 days or so. Freezing will not destroy all micro-organisms, so there is still some risk involved in feeding frozen products, but freezing certainly minimizes those risks. Also note that frozen fish that have been unthawed under refrigeration, should be fed within 24 hrs. (or discarded)


Freezing tends to also increase the concentration of thiaminase in tissue, so the shorter the duration in the freezer, the better. Little is known as to how thiaminase affects various species, and according to various studies the amounts found (even within the same species of fish) tend to vary as well. As previously mentioned most public aquariums tend to supplement to avoid deficiencies. (especially B1, vitamin E, and vitamin C) IMO fish kept in captivity require full vitamin & trace mineral supplementation to some degree or another. This is a non-issue if one is feeding a commercial pellet as the staple, or even stuffing "some" pellets into frozen foods, or supplementing via a commercial pre-soak such as Boyd Vitachem.


I posted the following years ago in another discussion, some good info for anyone feeding insects to their fish.

https://nagonline.net/wp-content/uploads/2014/01/NAG-FS003-97-Insects-JONI-FEB-24-2002-MODIFIED.pdf



Also, seeing as some are mentioning plant matter, the vast majority of fish species will do better consuming aquatic plant matter, vs terrestrial based plant matter, the latter typically containing anti-nutritional matter that at the very least should be cooked prior to feeding to at least reduce some of the antinutritional issues found in the raw form. This includes commonly fed items such as peas. Just because it's green, doesn't mean its good for a fish.
 

RD.

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thebiggerthebetter

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I am now feeding anchovies, about 3 inches in size

Delivered fresh to me and I repack on a per feeding basis and freeze it

I do not gut or remove any part of the fish before feeding

Not sure about the vitamins components though
That is what I was naively and ignorantly banking on too, that is, that a whole and natural, nothing added, nothing taken, frozen fish (but not frozen for too long as vitamins and minerals still decompose, just slower at lower temps) would be a complete, all-in-one nutrition package... but it is NOT.
 

thebiggerthebetter

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Thank you much!

RD. RD. "Also note that frozen fish that have been unthawed under refrigeration, should be fed within 24 hrs. (or discarded)"

This stumbles me. Did you mean to type "thawed", unfrozen"? Unthawed = remained frozen...

My usual packaging is 5 lb boxes and I have to thaw some of them partially or completely up to 5-6 times until the box is finished. Not to room temp but still cold, yet definitely not frozen anymore. If I read you right and if you meant "unfrozen", then I have been doing this very wrong... yet IDK how I could package up the frozen cuisine for my fish in smaller containers so that there is one per meal. I get frozen stuff by 200-600 lbs at a time... again most in 5 lb boxes or sometimes in solid frozen trays which I have to thaw and repackage into the same 5 lb boxes.
 
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