Really worried about my tank set up and my remaining fish :/ set the tank up 2 months ago, the first group of fish I put in were 9 neon's, 4 platys and 2 other orange fish. After 3 weeks in the tank and 15 new baby platys
I put in a crab (son was desperate for one ) and 4 guppy's last week. Yesterday I came home to 2 dead guppy's, a male and female, and a crab that was acting 'dead'. My remaining male and female guppy's are acting strange - lying on the bottom of the tank or floating at the surface barely moving their fins. Now my male guppy as developed huge black eyes and his face has changed from his usual blue/silver color to black. Now the crab is dead - definitely not acting! What am I doing wrong? Why are they dying and transforming??