Cloudy tank, fish rolling

HELP! A few weeks ago, I had a snail outbreak and they clogged up my canister filter and are destroying everything.I've cleaned the filter to increase the water flow, as this was causing a lack of oxygen. The fish were gasping for air.  I managed to get the majority of snails out, but since then, I've lost two of my new clown loaches (had them for 2 weeks). We've installed a new air pump and a bubble curtain to make sure that there is circulation. I also bought a powerhead. The water has been cloudy and I thought they were okay until now. My 5-year-old african cichlid is now losing color and floating upside-down and sideways. My pleco was rolling around and thrashing tonight so we did a water change.

Be nice...fish are friends!

But yes, I'm afraid many of us aren't well-versed in freshwater husbandry as we focus on saltwater aquariums here. I did freshwater for decades, but I barely remember any of it. Hopefully one of our dual-specialists will chime in.

Can you tell us exactly what the water tests showed? Are you using tap water? If so, did you use a water conditioner? Are any of the fish gasping at the surface or scratching? Or...are they just losing color and floating?

I think you solved your problem already... There probably wasn't enough oxygen as you stated. Your parameters all look fine for the type of fish you have. If your water is stagnant, it definitely will not be good for your fish. As for the snails, I assume they're MTS... If you get a couple assassin snails, they should help keep the population down or gone. It wont hurt to do another 25% water change. Sometimes stuff can build up in your filter that will get out into the water. So i would clean the filter soon too...

I would suggest another water change, but don't discard the old water.  Use that water to clean your filter media.  Basically fill a bucket with old aquarium water and clean the detritus out of the filter media.  Don't clean the filter media in tap water unless you treat the water first as the chlorine will kill the beneficial bacteria. (That is why I say use the old tank water.)

Clown Loaches are snail eaters but likely can't keep up with an explosion of tiny snails.  They don't eat the shells they just suck the critter out of the shell so a larger loach may not be of much use on a tiny snail anyway.  They are also just like any other fish in that they will pick at and eat a dead carcass or even a sick and dying fish.  It is possible that your Loach is killing fish, but more likely it is just taking advantage of the food source a dead or soon to be dead fish provides.

I also suggest you add an airstone to the air pump tube if you haven't already done so and make that a permanent part of your aquarium.

Sorry for your losses Ice !!!! Hope all works out for you . Now you have discovered the best place for info if you ever decide to make the leap to the salty side of aquariums . Good luck and let us all tempt you to the other side ..... LOL