neon tetra.

[GMazzle 83]

@seangee has a good point, I would try and make sure there are plenty of hiding places for him to go to if he is being picked on, Once you add more plants that well help. My ember tetras which are small compared to the other tetra like to hide out in the anacharis "forest" I made for them at one end of my sunken forest tank.

@Retired Viking thanks for that. I have plants ordered and awaiting delivery. I'm looking forward to their arrival.
Tetra is still doing his own thing, I'm not seeing him eating but I think he must be getting some kind of food from somewhere saying he is pushing through so long.

 

[Retired Viking]

Fish can go for several days without eating, they do not need to burn calories to stay warm like us.