Fish to (x)Gallon ratio question

[rba718]

This may be silly to ask but I'll shoot anyway.

When doing my research on fish, the article will usually say the minimum amount of gallons the fish needs. (For instance, Malawi Eye-Biter = 120 gallons)

Now, let's say the fish is in a tank with the proper amount of gallons and space it needs, will other similar fish with similar needs affect the original fish as far as tank space and livelihood is concerned? Basically, can they share the same amount of gallon and tank space equally?

This is also considering that all the fish as a whole are friendly with each other and are healthy.

 

[BushFishRox]

IMO when a site says a fish need 50gal, 75gal, 100gals ect. is referring more to the foot print of the tank no so much the actual volume of the tank...

as for sharing as long as the filtration is up to par then it shouldnt be a problem...

 

[cichlid2006]

i get annoyed when people just state gallons. the dimensions are so much more important.
you cant put an oscar in a 55 thats 4ft tall. simply no room to swim, a rather extreme example i know.

 

[Lady G]

I believe when sites state that, it is referring to one fish. For example (IMO) an Oscar is recommended at least 75g right (I know many places say 55, some less) anyway...taking that 75 and adding two oscars well, it just wouldn't be wise. Yep, with good water conditions and water changes, it COULD be done...but not really a ideal thing. Of course this is JMO.

I agree with cichlid2006 though...the dimensions of the tank are what is truly important.

 

[Alistriwen]

When you're talking about tank size there are two factors to consider. When a species is said to need x sized tank it usually refers to its swimming requirements. That is to say that some fish because of their size or swimming habits need more space to get around. The other factor is bioload or the number of fish you have and the organic waste they produce.

So for example a fish may need 150 gallons (although as others have stated the footprint is more important than the raw gallons but rarely are fish described this way in literature unfortunately) but that doesn't mean that it must be alone in a tank of that size. The bioload is the critical element when determining the number of fish you keep and that is affected by your filtration and how you do your maintenance.

If you had say, two fish that reuired a larger footprint it would be ok so long as the bioload wasn't excessive as a result. There are exceptions to the rule though, for example the oscars mentioned above. They require more space because of their size but also because they are messy fish that eat and excrete a lot. So while one oscar would do ok in a 75 gallon two would be a bit much. The tank would also be too small for one oscar to escape the other if it were aggressive.

Your best bet when trying to figure this sort of stuff out is to do it on a situational basis and look at the specific requirements of the fish you want and the specifications of the home you are able to provide them and see if it matches.

 

[benzjamin13]

The way I look at it is, as long as the length of the tank is 3x longer than the fish's full size and the width of the tank is the same length of the fish's full size and the height is 2x taller than the fish's full size, then it's perfect.

 

[rba718]

Alright, that sounds logical, kind of the idea I imagined but I wasn't sure.

How about for my main tank? I have a 75 gallon tank with 3 Bichirs and a Ropefish in it. They're the main fish, and they share the space with a C. Hujeta, and a Pleco. the Severums I have are temporary, (kept them because they look nice really.). I have a Rena XP3 and a Fluval 305 running on the same tank and I do about 25% water changes a week. Is this an appropriate set up or should I get rid of some fish?