Tank size versus Fish growth rate

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her209

Candiru
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Aug 4, 2010
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Does the tank size (from fry to juvenile to adult) have any bearing on the growth rate? I didn't think so but the anecdotal evidence says otherwise.

I have eight 10-gallon tanks drilled and interconnected to a 10-gallon DIY sump. All 10-gallon tanks are approximately 10x20x12in. In each of the 10-gallon drilled tanks, I have fry of various ages though they aren't mixed. In other words, fry in the same tank are the same age but not the same age as fry in another tank. Total water volume of the system is approximately 90 gallons.

The oldest two groups (about 5-6 months old) of fry were moved from their respective 10 gallon tanks into a single 29-gallon tank. Dimensions of the 29-gallon tank is approximately 30x12.5x18.5in and has a hang-on filter. In about a month to month and a half's time, the fry seem to have doubled in size already despite being in a "smaller" volume of water, albeit a larger tank. The fry still in the 10-gallon tanks have gotten bigger as well, but by no means have not doubled in size. I didn't control or monitor the amount of food fed or quality of water in each of the respective tanks.

In the very near future, I will be adding six 20-gallon long tanks to the eight 10-gallon tanks and swapping out the 10-gallon DIY sump for a 40-gallon breeder tank as a sump. Dimensions for the 20-gallon longs are 30x12.5x12.75, i.e, its just a shorter version of the 29-gallon. This should keep the water quality in the 10-gallons and 20-gallons the same and boost the total water volume to 240 gallons. :headbang2

Anyone else experience the same type of growth "spurt" when they move their fish from a smaller tank to a bigger one?
 
yeah i dont have evidence of this being true but i belive it to be true. fish with a larger tank grow at a faster rate then fish in a smaller tank. its almost as if they want to hurry up and grow into thier space, where as the same fish in a smaller tank is trying not to outgrow it to fast. i know it sounds foolish and i dont beilive they can physicaly halt thier growing but i guess they just eat more and develop faster with constant excersize in a larger tank
 
I believe water quality has a lot to do with it. In a larger tank, young fish can consume a lot of food and still maintain relatively better water quality while smaller tanks get dirty easier. Therefore, larger tanks usually lead to faster growth
 
andyjs;4392981; said:
I believe water quality has a lot to do with it. In a larger tank, young fish can consume a lot of food and still maintain relatively better water quality while smaller tanks get dirty easier. Therefore, larger tanks usually lead to faster growth
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You would think so, but the eight 10-gallon tanks are interconnected so even though the fish are in a smaller tank, the total volume is bigger.

Another "theory" is that the fish output a growth-inhibiting hormone (other than fish waste haha), but when they are transplanted into a new cycled tank, the hormone is non-existent and their growth rate increases. As the hormone builds up, their growth rate slows down.

Or another "theory" is that being in a smaller tank stresses them out regardless of water quality. But the fish in both setups aren't skittish.
 
my friend kept his oscars in a 20 gallon for about 6 months and they grew from around 2 inches to about 5 inches he moved them to a 100 gallon and they grew to 7 inches in like a month i had the same experience from my 55 to my 210
 
I read it is to do with the hormone released "g hormone?" which slows the growth of the fish, but also the water quality. ie if you change the water a lot and often there are more minerals and trace elements that the fish use. Hence the quicker growth. Diet is also a part, if you just feed tropical flake they are not getting all the vitamins and protein etc..
 
I also think its water quality, I grew out all my fry in 10gs then progressively upgrades into 20 longs etc. Just got to keep the water changes in large percents.

bonesb66;4403535; said:
my friend kept his oscars in a 20 gallon for about 6 months and they grew from around 2 inches to about 5 inches he moved them to a 100 gallon and they grew to 7 inches in like a month i had the same experience from my 55 to my 210
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I call bs, theres no way an oscar can grow 7 inches in a months time.
 
There are many factors that play into full adult (healthy) size of a fish.

You can cause shortend lifespan and massive amounts of physical deformity by keeping a fish in an environment not condusive to proper growth. There are many developmental issues that arise from improper tank size. Many people who claim "my fish died for no reason" fall into that category.

Water quality, water chemistry, lighting, diet, genetics and many other factors play a role.

When I set up the Amazon Exhibit for the aquarium in MN, I brought a 2 year old, 4 foot Arapaima up. It was packed into a tank that it could barely turn around in. Once it went into a bigger holding pool, then to exhibit, it grew like crazy. Within six months it was a 6 foot animal. It seemed like every time we turned around, it was bigger.
 
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