Flagtail has white stuff on his nose, please help diagnose.

[PDRed302]

Thanks to everyone for the comments and compliments

Woah What a tank! What's the stock?

3x Oscars: one tiger, one albino, one lutino
1x Common Pleco
3x Spotted Silver Dollars
1x Rotkeil Severum
1x Turquoise Severum
1x Firemouth
1x BGK
1x Marbled Angel
1x Convict
1x Senegal Bichir
1x Green Texas
1x Nicaraguan

Soon to be added:

1x Hoplarchus psittacus (true parrot) he's in quarantine now.

1x Blue Acara, currently growing out a group and waiting for them to pair up.