Is this true?

[Munkee]

I keep reading small references all over the place, that state, if clown loaches are kept in a tank too small for their adult size that a growth inhibiting hormone is secreted into the water causing stunting?

What if you have a 55G with 5 juvinile clowns and keep them there for 2 years, then move them up to a 125G? will they still be slightly stunted?

I am very curious on this matter, as I an ot sure if it fact or another fish myth.

[Martin Thoene]

Most fish species excrete growth inhibiting hormones into the water. It's one reason for the myth of fish growing only to a given size in a certain tank size. For a lot of species there is some truth in this but certain other species do not generally seem to hold to this such as Pacu and Redtailed Catfish as two examples which just grow and grow.

One reason that breeders do so many water changes in grow-out tanks for young fish is not only to control Nitrates and dissolved solids, but to dilute these inhibitors to growth.

Stunting can be detrimental to fish because it can affect the internal organs relationship with the overall body size and most probably affect overall longevity.

5 juvenile Clowns in a 55 given good food and regular water changes for 2 years will likely grow reasonably well up to around maybe 4-5" body length (not total length). Moving up to a larger tank earlier than within 2 years would be preferable because at 4" plus they need a lot of swimming room in order to exercise their bodies which will be a factor in normal development. A 55 isn't really long enough for fish that size IMO.

Early stunting will inhibit proper further growth even if the fish are then moved up to a larger tank. I have two Clowns that were adopted from someone. She said she had them for over a year yet they were both only around 2" standard length (body). They were kept in a 20 long. I've owned them for at least 3 years now and they are only just over 3" SL, despite never having been in anything smaller than 120 gallons since I got them. So you can see that thier early cramped quarters have had a detrimental effect. They both ought to be way bigger given thier known approximate age.

Martin.

[Munkee]

Thank you Martin, this is what I was always under the impression of. I was just trying to make sure it was not another "myth".

Your help is much appreciated.

[Diana]

The original use of growth hormones in fish was to help the fish survive a temporary hard time. For example, fish in a pond that is drying up will be exposed to increasing levels of growth regulating hormone, and their growth will slow down. When the rains come again the pond fills, streams flow again and the growth regulating hormones are diluted, washed away, and the fish grow again. They have not been exposed to the growth regulating substances for long enough to permanently hurt them, and they have survived the drought or dry season.

In a small tank with (likely) inadequate water changes for several years many fish do indeed end up stunted.

I remember seeing a picture of a catfish (Pleco? Something else?) in a 10 gallon tank. For whatever reason the owners never thought to get a larger tank, but the fish had grown longer than the tank, and could no longer turn around, or even move properly. All it could do was wiggle. It was sort of wedged in there, corner to corner.

[MoonPye]

I remember seeing a picture of a catfish (Pleco? Something else?) in a 10 gallon tank. For whatever reason the owners never thought to get a larger tank, but the fish had grown longer than the tank, and could no longer turn around, or even move properly. All it could do was wiggle. It was sort of wedged in there, corner to corner.

OMG what sane person would actually keep a living creature in those conditions??? That is HORRIBLE and abusive.

[Blue]

I remember seeing a picture of a catfish (Pleco? Something else?) in a 10 gallon tank. For whatever reason the owners never thought to get a larger tank, but the fish had grown longer than the tank, and could no longer turn around, or even move properly. All it could do was wiggle. It was sort of wedged in there, corner to corner.

OMG what sane person would actually keep a living creature in those conditions??? That is HORRIBLE and abusive.

[Botia Robert]

So you can see that thier early cramped quarters have had a detrimental effect. They both ought to be way bigger given thier known approximate age.

Martin.

This is interesting. So do fish have maximum sizes or can this phenomena be manipulated to achieve larger than normal sizes. For example, If you chose a really fast growing loach such as Yo Yos and put a small school of them from early age into say an 8 foot tank with good filtration, good feeding, etc and a minimum of dithers would they exceed their expected size of 6 inches? If so by how much?

[Martin Thoene]

No Robert any animal has a theoretical max size based on genetics etc.

Humans aren't confined in an aquarium right? If you give them good conditions and lots of food they just grow outwards not up right? You can theoretically selectively breed for size (hence tiny dogs and huge dogs) but with every single generation of fish they can be stunted by incorrect conditions.

Martin.