skin shading

Tank size : 2*1*1.5 feet. Length, width and height. Tank mate: 2 guppi, 2 sword tale, 4 red tetra, 3 white moly, 3 black molly, 3 yellow molly, 5 hockey, 4 mickey mouse platty, 1 sunset platy, 1 betta, 1 zebra danio. Came back from 7 days vacation. Had cleaned tank before going and putted...