# Feeder fish: good or bad?



## divine

I have read stories about how there are growth inhibiting hormones in feeder fish, particulary goldfish. I have heard this a few times on this forum. Does anyone have references to studies or reports on this? Basically, I am looking for some hard evidence, not just a friend of my friend said they are bad or good.

I feed my red belly piranhas feeder comets or fatheads at least once a week along with sole, cod, sea bass, prawns, krill, and very rarely a small piece of chicken. I think they do well as far as growth goes.

In another thread someone thanked everyone on this site for there helpfulness and respect towards one another. I would like to thank everyone as well. The members make this site great.


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## john1634

honestly i have heard that almost everytime i read the forum. never seen any hard evidence either, it has been weeks since i have fed goldfish to my p's since i heard this rumor or what ever it might be called


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## channafreak

Nutritional deficiencies aside........... I think the biggest concern is the transfer of parasites, both external and internal. Feeding them once in a while is ok but I would quarantine the feeders and treat with a broad spectrum paracide to be safe. I have lost fish this way before. Now I dont use feeders as a result. Nothings worse than seeing an expensive fish die because of some 5 cent feeders.


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## Judazzz

I'm by no means an expert on this (far from it!), so I can't really give an answer to the question, but here's some things I Googled up (keywords: thiamine, B1, thiaminase)

Fact: the enzyme Thiaminase breaks down Thiamine (Vitamin B1).
Fact: goldfish and other Cyprinids contain Thiaminase.

The purpose of B1:


> Vitamin B1: (Thiamine) is stored in the body to a great extent. Evidence of a deficiency appears within a few weeks. The function of vitamin B1 in the body of fish is to form the active part, or 'coenzyme' of certain enzymes involved in the metabolism of carbohydrates, particularly of pyruvic acid when a vitamin B1 deficiency interferes with carbohydrate metabolism, a number of characteristic symptoms appear *A lack of vitamin B1 causes loss of appetite, a failure to grow, general weakness, nervous malfunctions and muscular action stoppage in the caudal fin. If they do not get vitamin B1, they will finally die.* The symptoms disappear very slowly when given vitamin B1 in their food.


Source: THE EFFECT OF VITAMINS ON TROPICAL FISH

Obviously our piranha's get vitamine B1 from other food sources, but feeding goldfish at least partly 'neutralise' the effects of the B1 fed through other food sources - it _is_ an health issue, there's no question about that.

I've seen many people that said "I've been feeding my Reds goldfish for years, and they're all healthy and measure about x inches"
The question that remains (and can't be answered): how big would these fish be without the goldfish diet?
The effects of Thiaminase may not be visible to laymen eyes such as ours, but it doesn't mean there are no effects. Maybe the lifespan is cut in half when regularly feeding goldfish, and we are blissfully unaware of that.
No matter what the true effects are, the chances of compromising your piranha's health when regularly feeding goldfish or related fish is very real: the irony is that it's easy to avoid by getting other types of feeders.


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## scent troll

live foods are actually exteremly good for your piranha IF you know what to pick. gold fish are a the equivalent to eating mcdonalds for a days intake. i preach variety all the time becuase to stable any diet on one certain thing even if good, can be bad. you need to feed piranha a variety of live and packaged foods. i personally buy cut steaks and fish filets for my red. i store them in bulk for a good few months and thaw a piece at a time. i feed him feeders now and then, mostly cichlids but NEVER straight from pet shops. always always always quarenteen. like the guy said above, it sucks to loose a prized fish to a 5 cent feeder. ive had it happen to me with my beautiful 7 inch rhomb. i learned my lesson and people like me try to steer others clear of the horrid sight of walking in after a hard days work to a dead piranha youve looked forward to see. to add insult to injury, the damn feeder will probably still be alive...


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## divine

Thanks for your informative post!

From what i understand fish need Thiamine which is vitimin B1 in their diet. Thiaminase is an enzyme that destroys thiamine. A deficiency or lack of B1 (thiamine) will cause loss of appetite, a failure to grow, general weakness and a few other things. If it get bad enough the fish will die.

I looked up Thiaminase and found this site than contains a list of fish the do and do not contain Thiaminase.

http://www.austinsturtlepage.com/Articles/Thiaminase.htm


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## RedBelly Dom

when my rbps got about 2 inches all i fed them was goldfish. Then i found out all the bad things about them. but they grew fine when i was feeding my ps goldfish.


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## Judazzz

divine said:


> Thanks for your informative post!
> 
> From what i understand fish need Thiamine which is vitimin B1 in their diet. Thiaminase is an enzyme that destroys thiamine. A deficiency or lack of B1 (thiamine) will cause loss of appetite, a failure to grow, general weakness and a few other things. If it get bad enough the fish will die.
> 
> I looked up Thiaminase and found this site than contains a list of fish the do and do not contain Thiaminase.
> 
> http://www.austinsturtlepage.com/Articles/Thiaminase.htm
> [snapback]991910[/snapback]​


Yup: Thiamine is another word for Vitamin B1, Thiaminase is an enzym that destroys Thiamine.
Piranha's get B1 from their food, but the Thiaminase in goldfish, minnows, rosy reds, barbs, danio's and other Cyprinids may cause a B1 deficit, if fed in large quantities.
If you feed some goldfish once a month it certainly won't affect your piranha's health, let alone kill them, but if you feed large amounts of goldfish, it might have serious consequences for your piranha's health, often not visible, but that doesn't mean it's not happening.

Thanks for that link, btw: interesting read









RedBelly Dom: you say your piranha's grew fine, which I'm not argueing against. But how do you know they have grown as big as they could? How do you know nothing's going on on the inside of your Reds? Just because your piranha's grew and are (or appear) healthy, doesn't mean nothing had happened.
There's more than likely no reason for you to worry about your fish (especially if you stopped feeding goldfish on a regular basis since), but out of the blue assuming nothing has happened to your fish doesn't mean it's indeed like that - how could you know and proove that?


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