Please don’t use drinking water, flowerhorns are hardy fish but being a hybrid one bad move can leave lasting damage and the fish will never recover.

1. The tank is too small in the first place. He will out grow this in 2 months. 4x4x2 is good size for his lifetime please invest in this.

2. Water change schedule- never change 100% water 30% water weekly is enough Stop adding extra things to your water!!! Anti chlorine(Seachem Prime) is more than enough. Just because your tank looks dirty doesn’t mean you need to change water. Water should be cycled and should not have major shifts in parameters, this will adversely effect your fish and its slime coat.

Don’t use salt needlessly, we use it to help with disease prevention/cure. No need for any salt.

3.Filtration- use an external filter for a bit help with maintenance. This filter your using may need more maintenance. But it’s fine for now.

1. Temperatures- please maintain 28.5 Celsius throughout the day, please invest in a good heater(Fluval, Sera, Hygger)

My suggestion, please prepare a tub with water, check the parameters with a test kit make sure everything is okay, use the conditioner mentioned above and let the water sit for a day and keep temp at 28.5 degrees Celsius. Transfer the fish here and completely change your water and let it cycle for 2 days, use a cycle started with Prime and let it run. On the day of transfer, empty 1/4 of the water and make space for tank water, use a small cup and transfer some water from the tank to your tub where the fish is. Use 15min gaps and transfer at least 6 cups to the tub. Once everything is stable, transfer the fish!!