I am currently running a 135L freshwater planted aquarium, which had 1 Siamese fighting fish, 1 cat fish plus about 12 of each neon and cardinal tetras. This was running like this for around 2 months with no problems. 4 days ago I introduced 10 lamp eyed tetra and over the pass 2 days I've lost the fighting fish and around 10 of the neon/ cardinal tetras. I noticed that some of the tetras were missing their tail fins!!! I've since removed all the lamp eyed tetras thinking that they were the problem but still I've had 2 more deaths. Can anyone shed any light of this pleas?