I generally agree with CJ on his post above especially in the context given. I would point out that there can be a problem if there are multiple planktivors (GShiners , tshad , gshad etc) in a system all competiting for the same basic food. This can impact yoy of other species as well like BG and LMB. The food web is so complicated and diverse it can be very hard to gauge and next to impossible to anticipate correctly the possible changes. Generally the more species you have the harder it is to manage all the potential interactions. Probally not something to worry too much about. I would be cautious of starting with multiple planktivors but it could be done with proper mgt. in the right system.