Fwapp
Fish Crazy

Ammonia - 0
Nitrite - 0
Nitrate - 15
I bought 11 rummynose tetras last week, the last in the shop (it was closing) and they have settled in well, shoaling nicely and eating. I noticed this chap with an odd tube type 'growth' on his side today, and I don't know what it is, or how to treat it. When viewed from end on, the growth is 1-2mm extra on the normal body (if you catch my drift.
He's eating well, and lively. Tank is well maintained, and has been established for a couple of years.
Tank is an AR620 with internal hood filter (think aquaone 620), plus tetratec ex700. 20% water change weekly, and monthly filter maintenance.
Daily dose of tropica tpn+, and co2 injection
Fed on mix of flakrs and improvit gamma
Can anybody offer any advice on how to get this chap back on his, er, fins?