What's wrong with my Blue Phantom?

[Mol_PMB]

I've had my Blue Phantom L128 'Orinoco' for nearly a year; he was a wild-caught juvenile fish.
He always went through phases of being shy and then outgoing. For the past few weeks he has been particularly shy and I have only had brief glimpses of him. Tonight he happened to come out a bit more while I was watching. At first I was pleased to see him, and then he turned round so I could see his right-hand side. There's something very odd - a big patch of apparently faded-out skin just behind the eye. It's just on the one side, the other side looks perfectly normal.

I've attached a couple of photos showing this. I know the pictures are not ideal but based on the last few weeks when I've hardly seen him, it's realistically the best I'm likely to get.

He has been in the same tank since I bought him - it's a 165L tank and the other fish are 9 tetras, 16 cories, 6 otos, one apisto and one ram. All of these seem in very good form, with the exception of a couple of the cory oiapoquensis that have been a little lack-lustre recently after I went away for 10 days and they didn’t get fed.

My soft water is typically pH 6.5 (but varies a bit), KH <1, nitrate <40, TDS approx 100, obviously ammonia and nitrite zero. I change about 50% weekly. Food offered includes fresh veg (courgette, bell pepper, spinach, and other veg), new era pleco pellets and tetra pleco wafers, plus a variety of live, frozen and pelleted protein for the tetras and cories. Substrate is sand and the decor includes some large 'slate waste' rocks providing several caves where he normally lives.

Can anyone suggest what the problem is and what I can do to help him?

Many thanks,

Paul

[Silurus]

Are you sure it's not a heater burn?

[Mol_PMB]

Thanks. I did consider that, but the heater is guarded. I'll have a closer look and see if there are any gaps in the guard.
If it is a burn, are there any treatments to help it heal?


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[Mol_PMB]

Sadly he died this morning. I can't find any gaps in the heater guard where he could have got a burn and I'm rather baffled.
RIP Orinoco

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