angels getting bloodfin?

[sw-addict]

I have a friend with a 135 gal tank that has been running for 2yrs plus, in it he has 16 2-3, inch angel fish, 5 dime sized fish he calls selvineys and one 10" chocolate pleco. The filtration is 2 of those waterfall type filters that were ordered because the lfs don't carry the big ones, and a very large canister, in them he runs carbon,the amonia stuff, and varying other types of porus media, plus filter polishing pads that all are replaced monthly minus the porus media. Water changes are done bi-weekly at around 30%. Nothing new has been added in the last 3 months decor or fish. He feeds flake food moderatly, daily. We checked his water with a dip strip type test and the nitrates were in the hi/ok zone. Anyways the angels are getting a blood color in the base of their fins, mainly dorsal and one has devoloped a growth the size of a b-b with the same red edge. Any ideas?

 

[Zagz]

My first inclination would be water quality. Has he tested for ammonia and nitrite and nitrates? Specific numbers would be helpful. Also doing water changes weekly would be best. Using ammonia blocking products are not recommended as in a well cycled tank, ammonia is converted by the beneficial bacteria. They can also throw off the real ammonia readings.

I would test the water and then do a large water change of 50%.