Clamped fins usually mean you either have poor water quality or parasites. Check water quality, if it is good then that's not the problem and parasites become highly suspect. Try treating for parasites (especially flukes) with an antiparasitic medication.
The fin on the top/back of all fish is called the "Dorsal Fin."
A dorsal fin, (or top fin), is used to steer the dolphin, and to help it balance.
why does my pet betta have holes on his top fin
Dorsal fin
A dolphin's fin is rounded at the top, but a shark's fin is straight
no a shark can not swim without it's top fin
It's top fin.
it is the fin on the top near the back of the fish
The dorsal fin, and it's used to stabilize the dolphin while it's swimming.
I think that the largest fin of a perch is the first dorsal fin, the one that is located on the top of the fish and is spiny.
A dorsal fin is the one on the top of the fishes back.
The "DORSAL" fin is the fin fish have on the top of their back. It is often shaped a bit like a triangle or sail.