My largest discus recently had a lump come up. He's about 20cm and the lump is only on the right side about in the middle of his body approximately 1cm diam & raised at least 3mm. Since this lump appeared he is swimming slightly down when he's just in the one spot [he always hangs out around the bubbles] but not a complete headstand. Still eating & chasing the other discus [he is top dog].
I have tried Epsom as the first thought was bloat/constipation and when that did nothing I tried treating for infection with no success [tried tri-sulfa tabs and pima/mela on separate occasions]. The last fish I added to the tank was a single discus which was darting against things so I treated for worms with Kusuri and that resolved - this was over 2 months ago. From what I can find on other forums, I am concerned he may have cancer. Not sure what else to try so any suggestions on what else to try would be appreciated.
Water levels are good, no ammonia or nitrite, nitrates are always below 5ppm, pH is 6.5-7.0, temp is 28-29`C and we do water changes every week usually minimum 40%.