Deciding on the tank size; rule of thumb; guidelines...

[Viktor Jarikov]

Hi All,

Does any one know if a nice write-up exists on PCF or elsewhere describing how to pick a tank size for a given fish to house it for life, the rule of thumb (how did it come about?), or other rules/guidelines, etc.? Not really looking for a long article (albeit this would be ok if nothing short exists) but rather for something concise, sensible, within a page or so to refer people to.

Of none exists, a thread or a few on this exact topic reflecting a variety of opinions, hopefully some from experts, and the explanations would be good too.

I am talking about medium-to-large fishes, say from 6"-12" and up.

Thanks!

[MatsP]

My guideline is around 4L x 2L x 2L (where L is the size of the fish) - modified by the activity level of the fish - very active fish needs more space, so easily 6L in length, and perhaps up to 3L in width - depth is usually not that much of a problem, except for fish that are "more tall than long", such as Pteryphyllum altum (altum angels) and similar.

There is SOME discussion here:
http://injaf.org/articles-guides/unders ... ng-guides/
It uses a 6L x 2L x 2L guideline, along the same lines as I've given above.

--
Mats

[Bas Pels]

Personally I think the 4L*2L*2L rule of thumb Mats refers to is only applicable for quiet swimming fishes, which do not need company of their own

I would not use it for Pangasius, which are very acvtive and nervous when alone, for instance.

For agressive fishes the rule does also not apply

But for the larger catfishes, and that is where this rule is used on this forum, it does have it's worth

[Viktor Jarikov]

Thanks guys. Mats, an excellent link. I much appreciate it.

Forgot to mention a third obvious option in the OP: one can offer their view and opinion on the subject in this thread. I only ask, please, that, if possible, it'd be experience-based and well-explained/argued.

[Barbie]

I think that this really is going to have to do with the individual opinion. What I consider a minimum will be excessive to some, and I know I have horrified fish keepers a time or two with large specimens crammed in small spaces (always temporarily). Ideally I prefer to go with more of the 6L dimensions that Mats mentioned, but at least at my house, I do not always house fish in the tank they will spend their last days in, either. That too is liquid.

I'm not sure if that really helped any, but again, it is just my opinion ;).

Barbie

[Richard B]

In terms of 4x2x2, I first came across this suggestion/recommendation in conversation with someone (I forget who) at one of the CAGB shows in Amersham (catfish assoc Great Britain who were the predecessors of the CSG). At the time it seemed generally feasible although inappropriate for species like corys as the tank obviously seemed too small. Also some fish were incorrectly sized like RTC which was thought to be a 2' fish not a 4' fish. At that time no real consideration had been given to the exceptions like chaca where the tank can be smaller or pangasiodon where the tank should be much larger. At the time it appeared to that it seemed to be an almost accepted but unwritten guide. I've heard many opinions since then but this is the only thing that has stuck.

This 'guide' is still insufficient when you consider the territory of some tanganyikan cichlids which I believe have 20 square metres of territory as their own or perhaps more, the like of which cannot be replicated in the home aquarium.

[Jools]

I've mulled this over from time to time. The best I've ever come up with is the three dimensional using TL, an index based on the activity level of the fish and an index based on the sociability of the fish. But that then only talks to the largest requirement in the tank, you need something else again to work out how many fish in that tank.

Jools

[Psy]

Just some experiences.

6x2x2 or 4x2x2 seem like good starting points. Its going to depend on the fish. 4x is not enough for big barbs (Tinfoils and maybe Bala sharks). 6x may not be enough either, but going strictly on size, a 75 or 120 gallon might be ok. Its really not.

A counter to that might be the common solo Oscar tank. Its a big cichlid reaching 18 inches potentially. Personally, even a 4ft tank isn't too much of an issue because they're quite slow moving. I think a 4ftx2x2 120 gallon would be perfect even though it violates each length. Most of my cichlids pick a rock and sit under it even in big tanks.

Show tanks though, I think bigger is better. I currently have some convicts and salvini cichlids in a 5ft 80 gallon tank, which is handily over 6x2x2 but I keep wondering what a group of Apisos or cory catfish would look like.

One exception though. The local zoo has some tetras in a 10x5x4 ft or so tank. With no structure, no predators, and not enough fish for the size of the tank, they just spread out and you can hardly see them.