what makes a shrimp go limp?

[morning breakfast eat]

Hi all, i added 3 yamato shrimps into my 6-wk tanklast week. It was fine for the first few days but one if them started to limp after my water change on sunday. It has been 4 days since. The shrimp is not yet dead but it is dragging its legs on the ground. Do u know why this happens? what should i do now?

btw i dont have test kits so dunno the parameters of my tank.. But it is 40litres. Inhabitanta are 6 neon yetras 1 guppy and 3 yamatos. Tetras were added 5 wks ago

[deone]

What kind of tetras did you add and what size are the tetra?

[morning breakfast eat]

Neon tetras about 2cm. Guppy abt 3cm. Yamatos about 3cm. They are not afraid or anything they dont hide and they eat well. Also i just noticed 2 of the 3 molted today. Not sure if that matters

[morning breakfast eat]

Neon tetras about 2cm. Guppy abt 3cm. Yamatos about 3cm. They are not afraid or anything they dont hide and they eat well. Also i just noticed 2 of the 3 molted today. Not sure if that matters