What formula do you use for stocking fish?

[Komodo]

I read that some use the one inch per gallon rule for stocking a tank while others use total gallons divided by two.

I know that I need to take the rocks and other decorations into account, but are these rules good to go by?

100 gallons of Malawi Mbuna would be according to the top formulas as follows…

Rule one:
One inch per gallon at 4.5 inches average per fish would be twenty-two fish.

Rule two:
Total gallons divided by two would be fifty fish.

A difference of twenty-eight fish? In my opinion, they can't both be correct. How do you know how much fish goes in your tank?

[emerald76]

There is no stocking rule. If you go by one inch per gallon, that is similar to saying 10 neons=1 10in Oscar. Yeah, right. And then volume/2 means if I have a 100 gal tank, then theoretically 50 fish of ANY size, temperament, etc, will coexist if I'm reading that correctly as I haven't seen it before. 50 oscars in 100 gal? NONONONONONO


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[mr_X]

None of this works for salt tanks. You have to figure out the ideal environment for each fish, their adult size, and of course their aggression towards others. Some fish are free swimmers that need a lot of space or they stress out, their immune system is compromised, and they end up dying from ich or some other disease.