Sudden Fish Aggression, Normally Gentle Fish

[rch7279]

I'm not sure if this is emergent, but I don't know where else to post it. I have 6 neon tetras, one glo fish, 1 guppy. The guppy had been sick for some time, and wasn't eating or getting better with meds so I took him out this morning to put in a hospital tank. He isn't the problem, immediately after I took the guppy out the glo fish started being super aggressive with the tetras. He is really going after all of them. No one is sick, they were all fine, normal, and happy until I took the guppy out. I don't know what to do, poor tetras are trying to hide but the glo fish keeps going after them and biting. Any ideas?

Tank size:6g
pH:7
ammonia:0
nitrite:0
nitrate:10
tH (total hardness my tests say):0
tank temp:76



Volume and Frequency of water changes:about 20% weekly, just did one yesterday

Chemical Additives or Media in your tank:melafix for when sick guppy was in there. Also some aquarium salt according to it's directions.

 

[WILDER]

I would issolate the glo fish and think of rehoming him.
Are they a shoaling fish as don't know much about glo fish.
Tetra shouldn't be really kept in less than 10 gallons as there shoaling fish and need room to shoal.

What's wrong with the guppy can you describe his symtoms.