I have 6 fish and at least 3 of them are as big as my hand

My tank is 25 L


What would be the best volume for them?

(I may split them up if they keep on growing) [COLOR=purple]

Wow I'm surprised your fish grew as big as they did in that size tank. Thats only a little over 5 (uk) gallons. What kind of fish do you have? Fancy goldfish need atleast 10 gals (38l) each and single tails need atleast 20 gals (76l) each.

My amounts may be off a bit but its close enough

I have read the rule of thumb for all fish is 2 gallons per inch of fish.

That rule unfortunately does not go well with the goldfish, that rule was meant to be for tropicals. Sadly still, many pet store employee throw all the fish in one bowl, so to speak, and apply the rule for just about every fish.
The tipoff that this isn't quite right should be the size difference between a tropical and a goldfish. The latter one is so much larger, and has so much more output of waste and ammonia, and a much higher demand on oxygen. It doesn't make sense to put a goldfish in the same category than a tropical.
Of course, a tiny little goldfish in the store doesn't look much different in size than a tropical, but take one home, and you'll find out that the goldfish starts growing and growing, while a tropical stays pretty much....well, tiny.
In simple terms, thats why we endors the 10 gl/fish rule, or even more for single tailed fish and extremely big fish. Of course, if you ask professional breeders of fancy goldfish, they'll tell you that their breeder fish get even more space than that. But thats an entirely different prospective, since the breeders most likely has big ponds and tubs, while most of us have aquariums at homes.
Either way, you not only do your goldfish a big favor when getting the biggest possible and affordable tank for them, it also helps the owner along greatly. A lot less maintenance comes from a bigger tank, less water changes, much more stable water parameters of pH and temperature, etc.
Once you are addicted to bigger tanks, you'll never go back. Speaking of experience here.....(founder of the GAA - Goldfish addicts anonymous...)

It's actually 3 gallons of water per inch of goldfish and 1 gallon of water per inch of tropical fish

Well with so many of my babies (well big babies) in my tank (my descriptions of them are in my quote) I HAVE to change the water every week or it goes brown!

Does anyone know how many Literes are in a gallon?

Not to worry I will soon get another tank, so they won't be so crowded.

I'm a woman with small hands so the fish are about , I don't know 10 centimeters or something.

They just keep growing !


I heard somewhere that fish will only grow as big as thier environment allows. Is that true or have I mixed gold fish up with another animal?

I fed them cucumber a few days ago and they liked it, but not the brocolli (they take after my little brother in that respect) *lol*

Saying they only grow to the size of the tank they are in is only true in the aspect that they have no more room to grow. They release growth hormones into the water and a tank too small would stunt them. It would be like putting a human child in a dog crate, it would only grow as big as the dog crate simply because it cant grow anymore.

Ahh I see, still I think its cruel to keep animals in a tiny environment.

yeah I agree. 10 gallons at least for fancies, and 15 to 20 gallons for commons/comets or shubbies.

I had a comet who when I started with goldfish was in a 1 or 2 gallon tank. The poor thing. He got so big in that tank, that he could barely turn around in there. I finally got him a 10 gallon, and he still kept growing strong. He eventually went into a 30 gallon. It really depends how long the goldfish is in that small of an environment to know how badly it would be stunted.

Good Luck