I'm not sure what you mean exactly- a net just for catching fish? I have always used the green ones- the black one may be better, but I don't have any experience withthose so I don't know for sure, I would guess though that they're all about the same. Some fish (notably catfish) can get their fins tangled in nets pretty easily, I find with them it's better to use something like a jar to catch them (I used a small colander once in a pinch, that worked). Are the black ones marketed as something that's better for the fish? The size of the mesh is the only signifigant variable with the net that I can think of- so to stop rambling and answer yoru question- you may have paid too much but that doesn't mean your net was a bad thing to buy. Don't let the store guilt you into buying anything you don't want, they're just sales reps, not experts. It sounds like you want to do what's best for your fish and that's great- unfortunately some businesses find newcomer's enthusiasm as an opportunity to cash in, so be careful.