I have two juvenile (2-inch) comet goldfish in an established 30 gallon tank with a filter and aerator. They are very active all day and are always foraging and moving around; they are NEVER still. But recently I've noticed that after they eat, they stay motionless and just float around in the bottom corner of the tank for about 10 minutes. They look stoned almost. I feed them repashi soilent green in the morning and saki hikari pellets in the afternoon. Does anyone have any idea if this indicates a health issue?