Kuhli Loach

[Incitic]

Ive got a small kuhli loach in my 5 gallon atm with two other kuhli loaches and two tetras. Hes curled up at the front of the tank and mainly just sits there apart from odd spasms. He was breathing fast before but it has slowed now. What should I do?

Ammonia and Nitrite are at 0. The other fish are fine. I usually do a weekly 30% water change and dose ferts for my plants. ph is 7ish. Heater is set to 24, strip says 29, its a fair old though.

 

[WILDER]

Well the tank is overstocked with loaches, plus tetra need at least over a 10gal tank as they are a shoaling fish which mean they need room to swim.
Check the gill area to see if it looks inflamed, also do the gills look more shiny than usual, any fungus on them, any flicking and rubbing, also is the fish bloated or has it lost weight, has the colour darkened or gone pale.
Also check the anus to see if it's enlarged or red and inflamed, and what does it look like when the fish goes to the toilet.

 

[CobraGuppyMAD]

Mayby the tank is overstocked