Had to take fish home from work aquarium, they aren't doing well...

Thank you everyone for the advice.

I went downstairs this morning to check on them and the tank is now up to a much better temp (about 77) and all the fish including the angel appear to be doing much better. They are usually between 78-80 at work depending how how high the heat has been running so I did turn the heater up a bit more. It's "set" to 80 already but I know it runs a little colder than where it's set.

The red at the base of the fins has subsided a great deal though some is still present. Some fish including angel are still a little lethargic but when I put in some frozen brine shrimp this morning they all snapped out of it to eat. I went out and got the air stone anyways because it certainly can't hurt. Since they all seem to be doing much better today I'm going to hold off another day before doing a water change (though I will be watching them closely so this may change or I may just do a small one) More than half their water was changed during the move so I'm not concerned about ammonia but I have ordered a test kit and will post when it arrives tomorrow.

The filter shouldn't have crashed, it was only not circulating water for an hour tops and the canister remained full of *warmish* tank water during transit. I did rinse the filter pads in tank water because it hadn't been done a while and there was a lot of gunk getting into the impeller making noise when i reset it up since the move had shifted the detritus in the filter. I do have some startup on hand from my guppy tank if I should find this is the case once my test kit arrives.

I think the lesson learned for me here is that when I move them back I need to get a second heater going sooner so as not to have this temperature issue again; I think their tank was already dipping into the low 70s when I picked them up since the heat in the building was set at 45 and heater couldn't keep up. Won't let them get down to 68 again.

edit: here’s a picture of the fish.

HEAT UP THE TANK and let us know how it goes, no need to water change and stress them out more, just test the tank and if it tests high in ammonia or nitrites then add Prime OR Tetra Safe Start Plus - I'd forgotten that Tetra's version of conditioner not only adds good bacteria, but it neutralizes bad ammonia and nitrites (probably only for 48 hours like Prime) and then start the water changes and try to get your tank back in cycle - I did it and finally was successful after I started weekly 75% water change and a ton of Tetra. Fell right back into perfect zero's after that.

I don't see what the big deal is about using chemicals - what we're doing manually with a water change concerns chemicals but it doesn't mean that's the only way to fix a particular problem. Chemistry is chemistry. If the doctor gives you a pill to make you feel better do you take it or do an enema (every day)?

I have gotten so used to hearing about 75% water changes from this forum that I too do weekly 75% water changes. I have a bad habit of overfeeding fishes (I'm NEARLY cured) but once a week I clean my filter IAqualclear, best filter but biggest pain in the neck too), If the sponge is really slimy then it won't let water pass, if you replace your filter you loose a lot of good bacteria so if you wait until you've removed most of the water in the tank then put that in the bucket and squeeze out the sponge in there - it will get rid of the slime but keep most of it's good bacteria. At some point you do have to change the sponge - then I just add Tetra SafeStart Plus to help replace the loss of the bacteria in the sponge. I also soak the new sponge in the cleaner water in the tank during the water change. I am disabled and on oxygen and it takes me about 4 hrs per tank to do a water change because I can't carry much water at a time and don't use the long tubes that hook into your sink because it gets tangled up with my O2 cords (I can't wear a 5lb tank of O2 to get rid of the cords or I wouldn't be able to do anything) . In suction mode it also made my sink overflow all over the floor. Had to save a few curious fish too before they went down the drain.

I hired an assistant and she is wonderful does one tank in 1.5 hours and does beautiful design work, but given the Corona virus and her 2 kids that are constantly sick (schools are closed here) she's a huge risk for me, and while she works from home she seems to forget she should STAY home after work. She was recently sick and got tested and it tested negative. So I'm back to doing this myself - it's a killer. I'm thinking of doing the large water changes every 2-3 weeks and every few days suctioning out the excess debris and replacing the water with 4 gallons. It would be much easier on me.

Good job by they way - I didn't see your post until after I wrote mine. Sounds like you took some sound advice and saved your fish. If the angelfish love brine shrimp keep feeding it to them - it may keep them happy and a little fat LOL. You could also try Tubiflex dried worms - my fish love them more than the shrimp. Good job!