Confident in calling these fish brown bullheads. The difference between blacks and browns isn't as clear as one might hope. As
thebiggerthebetter
notes, browns have larger serrations on their pectoral spines, but I haven't found this to be very obvious unless you've got both of them in front of you to compare. However, I've found generally, black bullheads are dark brown to black on their backs with bright, brassy yellow sides and their fin membranes are a dark gray to black which contrasts sharply with their light-colored fin rays.
Browns vary a lot in coloration, but usually have some mottling and usually a duller gray to bronze ground color. And their fins are more uniformly brown colored, which is what stands out the most on this fish.
thebiggerthebetter
notes, browns have larger serrations on their pectoral spines, but I haven't found this to be very obvious unless you've got both of them in front of you to compare. However, I've found generally, black bullheads are dark brown to black on their backs with bright, brassy yellow sides and their fin membranes are a dark gray to black which contrasts sharply with their light-colored fin rays. Browns vary a lot in coloration, but usually have some mottling and usually a duller gray to bronze ground color. And their fins are more uniformly brown colored, which is what stands out the most on this fish.
