Hey all, Background: 29g tank, 5 danios, 6 neon tetras (well lost 3 tonite ;( , 1 three spot gourami and 1 Eb acara. The tank has been well established and running from a year. 4 days back 1 of my 6 tetras suddenly went missing, checked the whole tank, did not find it. Yesterday night when I looked at the tank at 11 pm before going to bed, all fish were doing ok. 10 am in the morning there were only 3 tetras. One of them has a white build up underneath its top fin on the blue part (like a white rash). Again took off 40% of water, checked all ornaments, no clue of those missing tetras. They were extremely healthy and been in the tank from almost a year. All other fish are extremely healthy too. Now my theory is: the first tetra died due to some illness then the other tetras ate it and got neon tetra disease and died? I'm seriously worried coz I dont want my remaining 3 tetras to die too. I don't get what went wrong, everything been running smoothly with no deaths in last 1 year, and now suddenly 3 fish dead in 3 days!!?? Please help me. Also, when I did wc to loom for those tetras, I found a weird transparent white colored pieces floating around near gravel, very similar to human saliva but transparent (definitely not fins, lil bigger and odd shaped than tetras fins). Also, the EB acara is still very young and very peaceful too, no chance it ate the teras, besides, the Acara is still barely 3" long. Please help me!!!!! I really don't want rest of my tetras, and potentially all the fish in the tank to die. Could this be NTD or fungal infection??? pH : 7.8 Ammonia : 0 Nitirite : 0 Nitrate : 15 Temp : 74.2 Thank you so much!!