How do you know how many fish you can add at once

[leo12345]

Is there a way to test how many fish your tank can handle at once?

 

[Phil Steel]

Is your tank establish and what size is it? That'll determine if the bio load is mature enough and obviously a larger tank can account for more fish.

As a rule of thumb that I follow and I have a red 625 XXL, is no more than 2 fish monthly.

But to answer your question properly, I guess there's no way to test aside from visually seeing that they are swimming around stress free!

 

[o2manyfish]

Too many variables for a simple question. What size tank... What kind of filtration... Existing amount of BioMass... Size & Qty of the Biomass to be added...What's the filtrations potential to rapidly respond to changes in Bioload... Maturity of system as a whole...

All of these affect the question. If you have a 29g tank you may be talking about adding 2 or 3 fish at once. I have a 750g tank and I have added 30 at one time and didn't think twice about it.

Dave B

 

[EeyoreIsMySpiritAnimal]

Is there a way to test how many fish your tank can handle at once?

If you are tossing handfuls of food into the tank daily and still getting no ammonia readings, you can probably add quite a few fish at once. Your biological filter (nitrifying bacteria population) will grow (and shrink) based on the amount of ammonia added or produced in the tank. If you have an established 220 gallon with 12 fish then adding another 5 or 6 at once should be ok, but if your system is new, then you need to go slow in order for the bacterial populations to catch up.