The loose guideline is one cleaning animal for every 1˝-2 gal
of tank. That would be for a more mature tank though so for a newly cycled 65 gal
, I would start with about 15-20 for now. It's best to start low and build as the waste producing bio load grows. As you already stated though, be sure the NH3
are zero before doing so. Also be sure the nitrates are at a reasonable level....
, crabs are not as necessary as some think. They can be a benefit but depending on the type of tank and potential nuisance algaes, a good mixture of different snail species will accomplish the same goal.