I have 7 red wag platies that I’ve had for months at my house no problem. They were very social and loved coming up to feed. I moved them to my husband’s empty tank at his shop. They are the only fish in there, sand substrates instead of colored rocks, but still many places to hide like the old tank. But now they never come out of hiding. Even to feed they wait until it drops to the bottom and quickly nibble it when I’m not there. It’s only slightly smaller than their previous tank, and their previous tank had my baby Oscar in it. Any reason these fish are acting like this? It hasn’t been about a month!