Hi everyone

[Koma]

I really had no issue with the fish so far, but thought I should have account here handy just in case...God forbid...
Anyway, I'm fairly new at keeping discus fish...they are at my care for about 7 months now. I have 13 fish in 500l tank (some apple snails in there as well), no plants a single piece of wood and one rock all at 28-29 degrees Celsius. I feed beef heart with discus additives and sometimes small amounts of fruit all mixed together. I do 40% wc on a weekly basis... If there is some advice or something I'm doing wrong please let me know so I can fix it.
Anyway, hello everyone