Am I dealing with Columnaris?

[IntrepidUT99]

Background:

Tank is a 20 gallon long, that has been up and running for close to two years now. Stocked with: Hillstream loaches, medaka rice fish and 100s of shrimp and snails. Heavily planted. As of three weeks ago I added 4 new juvenile medaka rice fish to bring the count up to 10. The current medaka population is 2+ years old, so nearing old age. A week after adding new fish, I did lose a senior Medaka. Today I noticed another of the older fish showing signs something is off. I am convinced I have something in my tank, however only signs of distress are with the rice fish.

Looking at the medaka rice fish in question , it appears parts of it are "washed out" or losing color and some fins are not in the best shape. Its also swimming slower than the others.

Current water parameters:

• pH 7.4
• Ammonia 0ppm
• Nitrite 0ppm
• Nitrate 25 ppm
• Phosphate 0.5ppm
• GH 9 (~160ppm)
• KH 4 (~70ppm)
• Water Temperature 71 F

Picture of the fish in question is attached.

 

Edited April 19 by IntrepidUT99

[Colu]

Could be columnaris that's a gram negative bacterial infections that spreads more quickly at temperatures over 75 and can kill in 24hr to 7 days depending on the stain I would usually recommend treating with kanaplex and jungal fungus clear fizz tabs containing nitrofurazone following this treatment plan kanaplex and nitrofurazone can be harmful to shrimp so what I would do is two full course of maracyn2 active ingredient minocycline back to back @IntrepidUT99

[IntrepidUT99]

@Colu Thanks for the feedback and breakdown for a possible treatment! I unfortunately do not have maracyn2 on hand, would have to order. Would you happen to know if API Erythromycin can be used in its place?

[IntrepidUT99]

@Colu Thanks for the feedback and breakdown for a possible treatment! I unfortunately do not have maracyn2 on hand, would have to order. Would you happen to know if API Erythromycin can be used in its place?

[Colu]

Erythromycin isn't my preferred choice to treat  columnaris as you have it to hand I would start treating straight away maracyn2 active ingredient minocycline or API fin and body active ingredient Doxycycline is what I would use both won't harm your shrimp @IntrepidUT99