clamped fins

Hey guys! new comer here:) My electric blue jack dempsey is showing symptoms of being sick but I'm not sure what he has. He is living in a 125 gallon aquarium with 1 blood parrot - 3 inches, 3 angelfish 2.5-3 inches, a common pleco 7 inches, 5 zebra danios and 1 otocinclus catfish ( I haven't...