With the shrimp thing, the bigger the tank the more you should add like if i were to do a 90 id put 2 shrimp in it.. please dont add any live fish or anything in it till the cycle is done. harming fish is just sad, people add damsels to their tank to help cycle but it truly is killing them, some servive but most die, and not to mention damsels are mean and hard to catch when you want them out..