help festivum dying!

[ice jack]

I have two festivum in a large community tank,they have always been fairly shy fish but yesterday i noticed one did not join the other fishs at feeding time ,they are about 1.5 inchs long. Today i noticed one of thefish lying on his side but colors are really vivid and dark when other fish came close he slowly rose and sort of glided away ,eventually resting by the side of a large plec in the tank.All his fins are very erect .This is a established tank and i have checked for ammonia,nitrate ect all ok. I have lost a couple of zebras lately but their symptons were different. any comments appreciated

[Star_Rider]

I would start with posting the water parameters(ammonia, nitrites, nitrates etc0 size of your tank, water change schedule etc.

have you noticed any other symptoms?

[jm1212]

what is the tank size?
what are the other inhabitants?
what are your water parameters?
what did the other fish die from?

[ice jack]

Its A 4 Ft.jewel Bow Fronted 250 Litre Tank. All Tests Were Within Acceptable Parameters According To My Test Kit. Other Fish ,angels ,clown Loachs ,keyhole Cichlids ,i Severum ,black Widows,corys And Plecs ,gouramis About 40 Fish In All. THE LAST FISH TO DIE HAD WHAT LOOKED LIKE A RED SORE OR BITE ON HIS SIDE ( ZEBRA DANIO) AND LOOKED LIKE HE WAS GASPING ,BEFORE THAT A RAINBOW FISH DIED ,SEEMED FATISH ,GASPING AND SWIMING AT SURFACE,THIS IS DIFFERENT VERY DARK COLORS,ALMOST SEEMS TO BE FLOATING AS OPPOSED TO SWIMMING WHEN IT MOVES ,SPENDS MOST OF ITS TIME ON THE FLOOR ON ITS SIDE (SORRY ABOUT THE CAPS!!)

[ice jack]

Came down this morning, it was dead plus a honey gourami, gourami i noticed was sulking at the back of the tank last night .Am going to do a 50 % water change dont really knowwhat else to do.All other fish look ok any advice would be nice.