back fin almost gone!!!!

[san sou]

My weather loache is losing it's back fin, plus his "feelers" around his mouth are way way shorter, i've spent the last hour here looking for answers, but can't find anything similar. Can anyone help me?

[Graeme Robson]

Can you supply us with more information?

Water parameters, occupants, tank size....etc. More info will enable many of us to help.

[YellowFinned]

Check your water quality, quickly!