Must they get big?

red devil

red devil

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Jan 7, 2003
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I have read in many places that you can control - to some extent - the size that fish grow to by the tank you keep them in and the amount that you feed them. Is it true? I know it is not universally true because I have seen some red tail catfish that were strangely deformed - unnaturally short for the width - and I suspect it was because they were kept in small tanks.
 
yes. . . .and this is not a good or desirable thing. it's called "stunting". fish, like people and all other animals, are constantly producing enzymes and hormones. with most animals, these chemicals stay within the body, but with fish (and probably amphibians as well), these chemicals are excreted through the skin and gills into the water. some of the hormones are growth hormones. theoretically, in the wild, this is so a large population of fish in a small area does not outgrow the available space (think a small pond stocked with too many bluegill). the hormones released keep anyone from getting too big, and maybe act as a way to reduce competition - if one fish doesn't get any bigger than another, than everyone still has an equal chance at survival. however, when a fish is kept in a small tank, or even in a large tank that doesn't ever get maintenance, those hormones build up, and the fish's own chemicals start to work against the animal, keeping it stunted and small even though it isn't really competing against anything else. oscar in a 30g, goldfish in a bowl, etc. . . . stunting causes deformities, shortened lifespan, decreased resistance to disease, organ failure, and color loss.
 
In extreme cases, such as the redtail cat you have seen, stunting can be a problem.

but in many cases, fish that do not reach their maximum book value size still live very long and very healthy lives.

Remember, many fish in the wild do not reach full size either. They have to capture or forage for their own food out there, sometimes in an aquarium the eat much better and get larger than they would in the wild on average.

As far as stunting goes, it just depends on the situation.

For example, I have redhooks silver dollars that are 10 years old. They are between 6 and 7 inches long. Technically, they should be 10 inches long. Are the fish going to drop dead tomorrow because they didn't get 'full size'? no. They show no signs of kicking the bucket yet lol

the larger the aquarium, the more food you can feed the fish without compromising water quality, and the larger the fish will get.

so, its not tank size directly that affects the growth of the fish, its the amount of food.

in a larger tank, you can feed more will still maintaining good water quality and the fish will get bigger as a result.

So, I agree with the post above:

use common sense.

put an oscar in a 75 gallon tank and you will be fine.

but don't put him in a 20 gallon and expect him to do well long term..
 
12 Volt Man said:
In extreme cases, such as the redtail cat you have seen, stunting can be a problem.

but in many cases, fish that do not reach their maximum book value size still live very long and very healthy lives.

Remember, many fish in the wild do not reach full size either. They have to capture or forage for their own food out there, sometimes in an aquarium the eat much better and get larger than they would in the wild on average.

As far as stunting goes, it just depends on the situation.

For example, I have redhooks silver dollars that are 10 years old. They are between 6 and 7 inches long. Technically, they should be 10 inches long. Are the fish going to drop dead tomorrow because they didn't get 'full size'? no. They show no signs of kicking the bucket yet lol

the larger the aquarium, the more food you can feed the fish without compromising water quality, and the larger the fish will get.

so, its not tank size directly that affects the growth of the fish, its the amount of food.

in a larger tank, you can feed more will still maintaining good water quality and the fish will get bigger as a result.

So, I agree with the post above:

use common sense.

put an oscar in a 75 gallon tank and you will be fine.

but don't put him in a 20 gallon and expect him to do well long term..
Click to expand...

very good reply. i agree completely
 
Keeping a fish small by putting it into a small tank and feeding it less food is like keeping a horse small by never feeding it, or how oriental women used to bind their feet to make them smaller. Is it possible? Sure. Is it desirable? Not in my book. I don't know, maybe I've seen way too many customers who are like, but if I put the BGK in my 10G it will stay small forever! And its really hard not to be blunt and say "because you've killed it".
Something I found helps to aid with the common sense usage, make a paper cut-out of the fish you have in mind and blow it up to the max size. For instance, if you are interested in an Oscar, make a cut-out (to scale on all dimensions) of the Oscar around their max length of 10". Then hold that cutout up to the tank in mind, does the fish have enough water to move in? Also be aware that "stunting" to make the fish smaller may not always work, and it may still outgrow your tank and live a very miserable life.
 
and no one can ever see/predict the shortened life span.... guess you could assume it was all well...
 
spirals said:
...Oscar around their max length of 10".
Click to expand...

Oscars get 15"+, in large tanks 18" :lipssealedsmilie:

Never keep a fish in a small tank just because you want it small. Take the Bonsai Tree; it is trimmed so it stays small.

They came out with the disgusting idea of a "Bonsai Kitten" soon after, where they keep a kitten in something like a vase so it stays small and is crippled and dies a horrible, suffering, and very cruel death.

Same thing as keeping a fish 6 inches or over in a 10g tank. Horrible suffering, organ damage, deformities, etc, etc.
 
rbishop said:
and no one can ever see/predict the shortened life span.... guess you could assume it was all well...
Click to expand...


true. and thats the hard part.

for most dedicated aquarists, the life span for a fish in a home tank I would think would probably be longer than it would be in the wild. No predation, constant food, clean water, no environmental impacts (eg. no dry season etc)

the problem is, the mortality rate of tropical fish on the whole is not very good. Most taken home from stores do not make it more than 2 years or so...many people kill them because the average aquarist (not people like us) do not change their water enough..
 
As contrary as it sounds, I knew someone who grew an oscar from 1" to about 18" in a 29 gallon. I always thought they would be stunted, but this one missed that lesson I suppose. I always told her he needed a bigger tank, but she just ignored me and kept treating him like he was a puppy. He was very well-fed.
 
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