Fish infection outbreak? DG and tetra affected.

[Jjensen187]

I don't normally post in the illness section unless I'm having a real issue and I need advice on what to do.

3 days ago I noticed my normally active dwarf gourami hanging out in the top corner of my tank. I knew something was up so I immediately did a water test and the results came up .25 ammo, 0 nitrite, 5-10 nitrate, and a ph around 8.2. The ph has been stable at 8.2 and the tank is cycled. I'm unsure why the ammonia showed up. Possibly with the addition of some low light plants, one of which wasn't doing so hot? Anyway I've been doing 50% water changes and using prime for the last few days with no luck. The ammonia seems ok but the gouramis health declined. Last night I noticed signs of rotting fins and white patches on the body. As soon as I saw this I dosed melafix but I believe it's too late. The gourami has lost the strength to stay upright and is now laying at the bottom of the tank barely gasping. I fear it's too late for the gourami.

I did notice the other DG of mine become somewhat territorial and chasing the other DG around the tank at times.

Upon closer inspection of the rest of my fish I saw that a rosy tetra of mine has white all around the upper jaw and it looks like it can't move it's mouth because of it. Same instance with the DG's, the tetras are aggressive towards each other at times.

I'll continue to dose melafix in hopes of preventing anything else occurring.

Any ideas as to what it could be? Sorry for the lengthy post.

Tl:dr gouramis fins rotted and had white patches on body, now laying at bottom of tank. Tetra has white substance around upper jaw/mouth, doesn't look like it can move mouth much. Unsure of what it could be.

 

[Koikid88]

Get rid of that ammonia.

The gourami sounds like it has fin rot, possible fungus or body slime, and possibly ammonia burn too.

I would guess lock jaw or mouth fungus for the tetra.

Stop doing 50% water changes, and start another treatment of Melafix antibacterial. After 7 days of dosing (I've heard half dosing for gouramis), do a PWC, and likely another 7 days of treatment before a %50 water change. Stir the treated tap water good, and let it sit overnight, stir again before adding.
You may also be dealing with fungus too, so you might have to treat with pimafix, half doses at the same time as the melafix.
This is just my opinion, some one else with more experience hopefully has additional answers.