Why does my 10" Clown Loach get blotchy?

[888fish]

Been raising loaches for the past 7 years. Purchased this 10" Clown Loach wild about 2 yrs ago, resides with 20 others (4"-7") in a 170G.

Problem: Each cycle I feed the community of loaches frozen thawed Tilapia or Market Prawns for every 2nd day for a total 3 feeds, the only loach that gets it's colors all blotchy is the 10". It also just pigs out on these meaty choices til it's stomach is round. And it takes about a week without feeding the Tilapia/MP for the colors to return to normal. It's behavior seems normal nevertheless. This blotchiness doesn't happen to it when feeding pellets.

Many thanks!

 

[Wailua Boy]

Wonder if its an allergy

 

[doviione]

Big Nice Loaches

 

[KNH]

Looks like normally coloration for a mature clown loach

 

[evabug1]

That coloration reminds me of what can happen with prolonged exposure to high nitrates. Not to say this is your situation. Try to find out where the tilapia you're feeding them is sourced. If it's farmed Asian, then there is a high likelihood the tilapia is fed pig and bird feces. You could try just feeding the market prawn on the days you feed fresh and see if there's any difference.