Missing Danio

[Alauahio]

My second last remaining Zebra Danio has been dying over the past four-ish days and I thought he was under a piece of wood. However I have looked everywhere and he just is not there! This happened about a year ago and I never found a corpse. What should I do?

 

[Naughts]

Check the filter but it has probably gone if it was sick. Do a big water change.

 

[Alauahio]

Check the filter but it has probably gone if it was sick. Do a big water change.

Thabks for the advice, I last saw her at the filter but she has since left, i'll do a water change like you said and check after.