This tank is 1.5 months old, cycled, 3 Gourami’s added 1.5 weeks ago. Temp 78, PH 7.5, GH 180, KH 120, 0 Ammonia, 0 Nitrites, 0-5 Nitrate. Planted tank, feeding flake food. All the fish have been doing great until today. I noticed this when the lights came on. Fish did not eat with the others. Any ideas? Thanks in advance!