Sick Cory or Genetics?

[fish_4_all]

I have a C. trilineatus that is not doing the best but surviving. Color is very pale with very few spots at all. The fish is also a lot smaller than the others. Is this fish struggling because he is genetically smaller and weaker or is he sick. The fishes belly is full of grindal worms as I take him and put him in a breeder every other day to make sure he eats well. He seems to eat like he is starving each time.

Ammonia:0
nitrites:0
nitrates:25-30
ph:7.2
PO4:2.5
GH:120
KH:120

Tank mates are all C. trilineatus. 4 adults and 13 siblings. All very healthy. No CO2 yet. fish was like this before lighting was increased. AC20 HOB filter. Substrate is epoxy gravel and plain river gravel.

Fish is 3/8 inch where simblings are 1/2 inch or more. Body is much smaller.

Is he sick, genetically weak or just not getting to the food?

 

[Devilishturtles]

I'd keep doing what you are doing now, and keep a close eye on him. Doesn't sound like anything is wrong. Are these offspring of the parents?

Some will naturally grow quicker than the others. But, they should learn to fend for themselves and get food. Little boosts from you are not a bad idea, like feeding him seperatley.