Loaches Online Forum

Sadly, one of my hillstream loaches died this morning
I have two and they've been in my 5ft coldwater tank for about a week and a half. They're tankmates are a common goldfish, black ranchu, an oranda and a fancy goldfish. Over about 5 weeks I've lost a ranchu, pearscale goldfish and two black moors. The tank is a relatively new set up at mine (about 3 weeks following an upgrade in size) but was bought off someone who had it set up & running so filter media should all be well established. I added Nutrafin cycle when I first set it up just to be on the safe side.
Ammonia: 0
Nitrite: 0
Nitrate: 5
I've attached some pictures of my loach, I could see blood on his underside this morning which was a shock as he's appeared fine up until today. The discolouration has happened since he died. The other loach appears ok, he's currently stuck to the back wall of the tank. I am currently trying to grow some algae on rocks and have just made a batch of the frozen food recommended on here. I was feeding them sinking algae wafers and frozen bloodworm and there is bogwood in the tank but neither seemed interested in it. I have a bubble wall, airstone and a fairly strong flow, they tend to like sitting my the filter outlet right in the flow.
I'd be grateful for any advice, I'm absolutely gutted and really don't want to lose any more of my fish

It looks like it might be some type of infection. Perhaps one of your fish had an infection when you purchased it and spread it to the others.

Any idea how to find out what it is or how to treat it? I really don't want to lose the other one too.

I'm not sure where you live, but if you have access to fish antibiotics, you might try using Maryacyn-Two (minocycline) and Marycyn (Erythromycin) as directed.

I live in the UK. I've come back this morning to find the other one hasn't made it either , although the goldfish seem fine Absolutely gutted. I never actually saw either of them eat, perhaps they were feeding at night but I can't help but wonder if they weren't actually eating and this is maybe why I've lost them.

Sorry to hear that. Sometimes hillstream loaches don't acclimate well and just don't thrive. That may be the case, but the red underbelly looks like an infection to me. Even though your goldfish are fine, you did lose several recently which makes me suspect an infection is involved.