Peppered Cories reacting badly to water change

[xixi]

Hi, everyone.

Background: So recently I've been combating ich and some unknown illness in my fish. I've been desperately running back and forth from my local Petco (my ride can't take me to the LFS) trying to figure out what to do best for my tank.

Finally, I bought an adjustable heater (the old one was preset to 72'F I believe) and have been keeping it around 76-80'F. I did a 100% water change and put in some bacteria quick start to help with the cycle. My gourami seems fine - he's eating and swimming around occasionally, but I've noticed he's been incredibly shy since the water change. My lyretail molly has sadly died, demonstrating a mixture of stiffening and thrashing gestures before passing. I'm devastated.

Current problem: My peppered cories are acting SO odd. I don't know if the water is bad or if they're sick. One of them stays at the bottom all the time, and the other two seem to float around aimlessly bent at an odd, flimsy angle. When they swim fast, it seems to be at a struggle. And then they stiffen again until they go to rest at the bottom. They weren't like this before. They were active and healthy. One of them possesses a fraying tail. I tried feeding them yesterday and they didn't even wanna touch the food. My gourami nibbled at it some, then went back to hide in the dark spot by the filter. addendum: I think he might be shy because I moved the decor around, so it looks different. Idk.

Tank and water: 10g tank. Tetra 10i whisper filter. Tetra whisper air pump. Aqueon adjustable water heater up to 20g. Have fish (3x cories, 1x dwarf gourami) for roughly 2.5-3 weeks. Two plants: bamboo (leaves stick out of the water, added today) and a generic freshwater plant. Water has been conditioned, ammonia neutralizer was added, Prime paraguard was added, and the quickstart bacteria cycle solution.

I bought a test kit and these are the numbers that came up:
Gen Hardness: 60
Carbonate Hardness: 40
pH: 7.0
NO2: 0
NO3: 20

I'd appreciate all the help you can give me! Please, and thank you so much.

 

[Old Scales]

OK first off, never do a 100% water change. Not because it messes up your beneficial bactreria(90% of it lives in your filter and on your surfaces under water), but because there's no way to perfectly match the water you took out. At most only change 60% at a time, waiting at least 12hrs before the next one.(24 hrs is better).
Next is, for fighting the Ich, just slowly raise your tank temp to 84F. About 2 degree rise every hour, no more. Keep tank at this temp until 5 days after the last Ich spots disappear. Then slowly lower temp back to 76F. Do NOT use salt as some will suggest as Corys are sensitive to it. The Ich meds are pretty hard on fish also. While temp is at higher level, run an airstone as warmer water holds less oxygen for the fish to breathe.
If you see white fuzz, white blotches or open sores on your fish or fin damage, you can get some Pimafix and Melafix and put in the water. Follow directions precisely. They are about the only meds that won't stress your fish.
Continue with about 50% water changes and redose these meds until you think all is well again. Make sure you lightly vacuum the gravel as some ich larvae live in it until killed. Make sure on ALL your water changes to match your pH and temperature precisely and don't forget the dechlorinator. Good Luck, OS.

 

[xixi]

*snip*

Thank you for your advice! I'll definitely go easier on the fish when I do a water change next time.

I'm still concerned about my cories, though. I don't know what's causing their behavior. It looks extremely unhealthy. I don't know if my current water parameters are acceptable or not? They're still slumping over and floating around at a weird angle. I don't know what to do.

Thank you.

I'd also like to add that ich is no longer a problem. however, I'm definitely going to keep an eye out and not use harsh medication for treatment next time, but their behavior started after the water change, not after the initial treatment.

 

[Old Scales]

Do you have an API master test kit. If not, I highly recommendit. The test strips are inaccurate. You want to check for ammonia, nitrite, nitrate and Ph. Test your tap water first thing to see what is in your water that you start with, then test your tank water.
They act like you might have too much ammo or nitrite. OS.

 

[xixi]

Do you have an API master test kit. If not, I highly recommendit. The test strips are inaccurate. You want to check for ammonia, nitrite, nitrate and Ph. Test your tap water first thing to see what is in your water that you start with, then test your tank water.
They act like you might have too much ammo or nitrite. OS.

Unfortunately, I don't have a test kit. Only the strips. I wanted to get it but it's way too far out of my budge. Do all stores, including my LFS, only provide strip water tests, or is there a chance they can give me a free drop test?

Thank you.

My cories seem to be acting better today. They nibbled on some pea yesterday, and today they're more active. However, they're still slumping awkwardly.

 

[xixi]

Now my dwarf gourami has a clamped left fin.