Wait, what's this? I've been following this thread and am confused I think. What do you mean by "Bull"?
Bull minnow, is a species of killifish native to the salt marshes of the gulf coast. Or at least that is the fish most commonly given that common name... Mummichog along the east coast are sometimes given that name as well. However, banded killifish, a related relative to both fish is also given that name. Since it is a strictly fresh to slightly brackish water fish, I am sure that is the species being referred to here. Banded killifish are an excellent pond forage fish, sourcing them is the only problem.