'Sunset' Honey Gourami Deteriorating After Quarantine

[anikom15]

Water parameters

• pH - 7.6
• Nitrates - <5 ppm
• Hardness - 10 dH
• Nitrite - 0
• Ammonia - 0
• KH/Buffer - 5 dH
• Water Temperature - 78

Tank mates (20 gal, moderate planted)

• 4 male guppies
• 10 cardinal tetras
• 4 false julii corydoras

I got a honey gourami of the sunset type. The fish store told me they are the same as any other honey gourami but are just orange. He was doing well in quarantine. By the end of quarantine (4 weeks), he was getting 2 flakes per day. I took him out of quarantine and into the main tank a week ago, July 2nd. The first day, the guppies chased him around a bit, but he flexed back and they backed off. The other fish now seem to ignore him. I don't think the tetras are nipping him at all.

An unfortunate variable was that in the middle of quarantine I was out of town, and I'm not sure if the lady watching the fish remembered to feed him (he's on a different floor from the main tank).

Yesterday morning he was hanging out at the bottom and being lethargic. I fed the tank and he made his way to the top. He's not at all aggressive about getting food and I fear he may not have been getting enough. I decided to target feed him with extra food and I was able to get him to eat until he stopped seeming interested. The tetras joined him and some of them are quite fat now, but I digress.

The rest of the day he would rest on the floor a bit, go to various corners of the tank and hang out, and then go back to the floor. He seemed stress but not in particular trouble. It looks like he has lost a bit of his dorsal fin, and he seems skinny.

The next morning (today), he seemed to be in worse condition, barely moving on the bottom of the floor. He came to eat a bit, but ate less than yesterday even when I tried to target feed him. After breakfast he hung out near the sponge filter (tank has HOB+sponge) in an almost vertical position (nose up). If any other fish came near he would move to another area and continue resting.

I decided to quarantine him again. I put him in a small holding tank with a floating plant and two flakes of food while I setup the holding tank and did a water change on the main tank. The water change went well and all the other fish are acting normal. The quarantine tank was setup with completely fresh water and prime but uses the same sponge filter that was in the main tank (I have no other filter). This along with the single floater should instantly cycle the tank. Before putting the fish in, I noticed the two flakes were consumed and he was active. I put him in the QT tank and he seems to be fine.

I have three theories. One is that he is normal and just acting weird, but my gut and experience tell me otherwise. I'm new to gouramis, but my understanding was that they like to be near the top of the tank. The other is that he hasn't been eating enough, is weak, and will starve without careful feeding. The last is that there is a bacteria in the main tank that the other fish are immune to. However, the last one seems unlikely because the original QT tank used partial water and sponge filter from the main tank, which would've brought any endemic bacteria with it.

[Colu]

What I would do is try feeding him up with 3 small meals a day add some frozen or live brine shrimp or daphnia to his diet  and I would add some aquarium salt 1 table spoon for 2 gallons that will aid Gill function and add essential electrolytes for a week 

[anikom15]

It seems he made a bubble nest today. I think that's a good sign. I think I will keep him in quarantine for two weeks and try reintroducing him again.