Redness at the base of angelfish fin.

[jazmin]

My Angelfish has redness at the base of his pectoral fin. I recently introduced 4 blue rams. One of them died. My tank also had other three angelfish, the partner of the one in the picture and two smaller ones that died yesterday. On my tank I also have 8 tetras, and a common pleco. What is causing this redness? It had happened once before and I did a water change and he got better. Yesterday I did a 50% water change. What should I look out for? or what can I do?

tanks size:75 gallon

ammonia: 0 ppm

nitrite: 0 ppm

nitrate: 20 ppm

pH: 7.6

temp: 80 F

 

[Colu]

The fact that they improved after a water change will lead me to suspect a water quality issue do you use a water dechlorinator like prime when doing water changes 

Edited August 8, 2022 by Colu

[jazmin]

I don’t. I just do a 25% water change. My tank is a planted tank. 

[Colu]

If you not using a dechlorinator that could be the cause as your water could have chloramines  in it and that could be the cause that will damage your fish gill's and the slime coat of your fish what I would do is test your tap water for chlorine and ammonia and I would start using to prime to treat your water when doing water changes @jazmin

Edited August 8, 2022 by Colu