what's wrong with these angels?

[infamous]

i just noticed that one of the lamarck angels in quarantine developed some type of infection. the area around the mouth, vent and the bases of the dorsal, ventral, pelvic and pectoral fins turned reddish. inspite of these, he is still eagerly feeding on whatever i give him. what do you think is causing this? could this be a sign of cyanide poisoning? bacterial infection? i must admit that i'm at wits end on what's causing this. i added tri-sulfa tablets in the tank to somehow prevent this disease from progressing for the meantime until i know the cause.
thanks!

 

[infamous]

almost forgot to mention that the other angel also has some reddish area around the mouth and vent but none on the bases of the fins.

 

[infamous]

ammo and nitrite are zero
nitrate is a bit high at 20ppm
ph is a bit low at 8.0
s.g. at 1.018
will the tri-sulfa be of any help? the qt is cycled-- will the tri-sulfa kill the biological filtration?
thanks!

 

[infamous]

hi terry,
ok, will follow what you said... but can i use minocycline(active ingredient of maracyn 2?) instead because i don't think we have maracyn here in manila? and at what dosage?
thanks!

 

[beth]

infamous, Terry said Maracyn Two. If you can get the saltwater brand that would be best, but, if not, the FW will do.

 

[infamous]

thanks beth and terry,
already did the waterchange and slowly raised the ph... now looking for some maracyn 2 or minocycline... will keep you posted! thanks again!

 

[jon.316]

Make sure you test your new water before you add it to your tank. Sometimes even prefiltered water has extremely high nitrate content that may cause your sick fish to die

.
good luck
jon