[FishieNut]

Rule of thumb for stocking.

Is it so many fish per gallon? So many inches per gallon? Is there a general rule of thumb -- big fish, little fish, fat fish, skinny fish... you know!

[BubbaWPB]

It really depends on age of your tank, other inhabitants, and what type of fish. But in general, I wouldn't go much above 1" of fish per 10 gallons, or one fish per 10 gallons... and since you have a 30 gallon tank and 3 fish already (along with other livestock) I'd say your tank is full. And yes, a 1" fish with a big round body would count as more load than a long skinny 1" fish...

[Ninong]

Originally Posted by FishieNut

Rule of thumb for stocking.

There is no rule of thumb for stocking.

Is it so many fish per gallon?

No.

So many inches per gallon?

No.

The myth that there is a "rule of thumb" is perpetuated by LFS employees who have no idea what they're talking about.

The reason it doesn't make sense is obvious. For example: One 6" koi has 10 times the mass of a 3" koi and one 12" koi has 10 times the mass of a 6" koi or 100 times the mass of a 3" koi. I use koi only because I'm familiar with their mass-to-length ratios. Obviously one 12" koi represents a lot more bioload than four 3" koi, which is why any "rule of thumb" based on so many inches per gallon is a joke.

In a marine tank, a single 9" tang represents many times the bioload of say three 3" dottybacks. In other words, you can away with a lot more small fish in a 100-gal tank than you can fish that are >6" TL.

Besides bioload, you have to take into consideration the fish's natural behavior. Is it an active swimmer or one that stays put? Is it an aggressive, territorial species or a docile fish that hides out all the time? A 100-gal tank is a great size for a Royal Gramma but marginal for any tang and much too small for the larger tangs.

[FishieNut]

Thanks,that helps emensely.