Discus turned dark and hiding

Problem

1. I have had a discus for almost year. He's always been a heavy eater and always excited to eat everytime I approach the tank but recent few weeks he has become spooked and dark. And stays mostly at the bottom of the tank. He picks at food occasionally but nowadays he isn't eating much.

I noticed a scrape initially on his body but seems to have healed up a bit but there seems to be another new scrape recently.. see pics below.

Currently I have added salt to the tank and anti fungal medication.



Tank/Water

4. Tank is about 18 gallons


5. Change water about once a week. 30%


6. Tank has been cycled and running for 8 months or so. With carbon filter + biological filter


7. I don't age the water but use anti chlorine. I did change the brand of anti-chlorine recently.


8. Parameters and water source;

- temp 28c

- ph 5.5

- ammonia reading 0

- nitrite reading 0

- nitrate reading 0

- municipal water

No tank mates

11. Used to feed twice a day with my beef heart mix. I feed the same with my other discus tank which is doing well.

https://i.imgur.com/KY8nTsy.jpg

https://i.imgur.com/KY8nTsy.jpg

It’s in the 18g cause it’s sick? If so change water daily at 50%. Is your tap water at a ph of 5.5? Test all reading out of tap. If no slime showing on fish (white patches) raise temp to 30c and add salt at 2 tbs per 10g.

He has been in that 18g by himself. I removed him from my other discus tank as the pair there was breeding. The tap water is about 5.5. PH has always been steady. I raised temp and added salt and will monitor.

There hasnt been much of an improvement. Treating him with Metro now for the next 3 days.

Nitrates 0 with a weekly 30% water change feeding beef heart twice daily? That's just not possible. Is your test kit out of date? Are you shaking the reagent bottles vigorously before testing? Especially bottle #2?

Just to note: It came from a tank that only had 3 discus. May have had this coming for a while. Bottom of hierarchy could have made him decline enough to become unwell. 1 or 3 is not a good number for discus to live a happy life.
Metro for 3 days will not do much.

Sorry the Nitrate usually is 10. Typo there.

He was moved to his own tank where he actually thrived for a while and was eating well. Now I'm on anti fungal meds hoping for some improvement as I see visible spots on his fins and wounds on his body.

Due to hole-in-the head symptoms I've been treating with Metro for a week now. Seems to be some improvement, but still seems spooked and not eating. Usually how long does it take for the fish to recover and start eating again?

Seems to be doing a lot better now after moving to a smaller tank. Treated with metro for 10 days before that. Now also started to eat and show some appetite. Will slowly increase the amount of food back to normal amounts.

Nice Hairy...we like good reports!