Cory With No Barbels And White Mouth

[greedo]

hello, recently i noticed two of my juliei corys have lost thier barbels and developed a white mouth kinda like bad lipstick.
any advice?

i live in the uk

Tank size: 140l
pH:7.6 - 8
ammonia:0
nitrite:0.1
nitrate:20 -50 mg/l
kH:110
gH:180
tank temp: 24'c

Fish Symptoms (include full description including lesion, color, location, fish behavior): seem normal but have a white mouth like bad lipstick and no barbels..... these are recent additions ie less than a month....no other fish seem affected.

Volume and Frequency of water changes:20% per week approx

Chemical Additives or Media in your tank: recently used antibiotic to get rid of blue green algae mess. weekly cycle and iron supplements at rec doses .have used primafix previously to treat fin damaged in transport/ fighting? with great success. water changed after treatment and carbon added to filter.

Tank inhabitants: 3x julieis, 3x peppered corys,6x pengiun tetra,8x xray tetra,5xserpea tetra,5xcardinals,5xglowlights,5rhummy noses,2x ottocinclus and 1x queen arrabesque plec

Recent additions to your tank (living or decoration): glowlights,peppered corys

Exposure to chemicals: antibiotic treatment at 20% dose

Digital photo (include if possible): dont have camera sorry

 

[WILDER]

You have a slight nitrite reading there water change.
I would think of adding another filter to your tank.
It's bacterial with the barbels going, and the white on the mouth if mouth fungus columnaris.
If the corys have lost all there barbels not good news as they need the barbels to find food with.
Substrate is it sand or gravel.

http/www.thetropicaltank.co.uk/hdcolumn.htm