quikv6

The ammonia may be the issue here. You tested at .25, but that doesn't mean it wasn't higher at some point. Small water changes with a dechlorinator that also temporarily binds ammonia such as Prime, would be a good path forward. Some salt could help as well.

Gannon...I echo your sentiments on the older Aqueon Pro heaters. I have had 7 of these running constantly. They are great. I did have one fail (off) after a few years. The light still let red when heating, but just didn't heat. The Inkbird alerted me to the fact that it failed. I found ebay to still have a few of the older models for sale, so you might want to check there. The newer Aqueons are terrible. I did go with 2 new ACO heaters on a newer 125 set up. Believe it or not, I only needed 1 to fully heat a 125 to 79 degrees. I keep the 2nd one in there as a backup, set 2 degrees lower than the primary. To be honest, I am really, really happy with them thus far, with the exception of the suction cups. As for longevity, that is still to be determined. I will probably hate that flashing "end of life" message so much, I may never see how long they actually will last. But so far, I have been very happy with the two that I have.

Nabokovfan87 brought up a great point. It would be best to test your tap water for PH, GH, and KH before we speculate and give opinions. If your tap is 6.0PH, with 0 KH, I actually think the aragonite would be beneficial in that case, solely to avoid any PH swing/crash. But lets find out what the tap is for sure before guessing..

I agree with not using it for the above fish. If you were going to stock with livebearers such as mollies, guppies, and platies, then I would consider it, especially of your tap water was softer than average, and below 7.0 PH. Otherwise it just shouldn't be needed.

Expel-P is a great guess. I would add some to the food as well. I have not had as much luck with Levamisole in the water column as opposed to the food. If they continue to spit the food, you may need Flubendazole, which has always done better in the column in a situation where a fish is spitting.

Airstone is a good idea. Some salt may help them adjust as well. As Colu mentioned...what are the KH and GH? Guppies generally prefer harder water, and could be facing a small "shock" if your water was vastly different than the water they came from.

What are your water parameters, specifically? Also, if it is indeed fin rot, you'd me much better off using a med that is more focused on gram negative bacteria, such as Maracyn2 or Kanaplex, as mentioned above. Also, don't underestimate the benefit from clean, clean water with fin rot. Small, daily water changes can really help, combined with the salt and medication.

There's a ridge that snap in and grabs, for a tight fit. It is definitely 2 pieces.

Part number 2 sits in part number 1. It is 2 pieces, and it definitely will pop out.

I'd be focused on getting the 1ppm of Nitrite down, personally. That could cause stress, and lead to illness.

Maracyn and Maracyn 2 together may negatively impact beneficial bacteria.

My recommendation would be anywhere from 25-50%, depending on what level the ammonia and/or nitrite is before the change. The higher it is, the more likely I would be to do 50%. If it's just at .25 or .5, I'd do 25%, and use Prime.

It looks like you may have a bit of nitrite from the test strip pic, but regardless, Ich-X is a great med for the ick.

I'd continue with small water changes for as long as you have .5 ammonia and/or nitrite. Anything .5 or under, I would use Prime to "Detox" it, though this is subject to debate. Ultimately, as the good bacteria builds, you will stop seeing measurable ammonia and nitrite. I have had good luck boosting a tank by squeezing out used filter media from another tank directly into the newer filter/tank.

I think the best treatment would be to get the ammonia and nitrite as close to zero as you can. You really want both to be zero. How long has the tank been up for? It appears it may not have completed it's cycling. Daily water changes (remember to dechlorinate), along with an additional airstone/oxygen will help. I have had success with salt as well. But the main thing is to get the ammonia and nitrite to zero. Welcome to the forum!

Could the municipality have added any treatments to the water? (Extra chlorine, heavy metals, etc)

Is the tank cycled. I noticed 0 nitrates, indicating a tank that may not have completed its cycle. (Or it may just be heavily planted.) A bump in the cycle can cause stress and potential infections.

It depends on plants, if that matters to you. I'd start with 1 TBSP per 5 gallons. You can increase slowly all the way up to 1 TBSP per gallon if needed.

What is the PH and KH out of the tap? You have 0 KH, which can result in a PH crash, which may be why your PH is so low. A crash can cause fish stress and lead to issues. Crushed coral may be your friend, and help increase the buffer (KH), preventing a PH crash.

It looks like it may be a prolapse. It may reabsorb into the body. I have had a couple of fish where that happened. I did a few 15 min baths in epsom salt daily, and fed very lightly, if at all. It took about a week to reabsorb fully.

Salt, and water changes every day would be my suggestion. You can try a different med, or just do a course of Maracyn 2 by itself with the salt and water changes. (Mixing 2 types of meds for bacterial infections is is generally not recommended, and can sometimes stress the fish, which won't lead to recovery.)

Questions 1 through 3 above will really help. Regardless....I think adding a bit of aquarium salt is a good idea. You can start at 1 Tbsp per 5 gallons.

Yes, it can....though eating is a good sign, along with an opportunity to add some meds to the food. Colu had posted a good recipe for adding Kanaplex to the food. I think that would be a good suggestion in this case, along with salt and clean water.

Clean, clean, clean water (Small water changes everyday), along with salt car really help stop fin rot, and allow the fins to grow back. (This takes time.) In your case, I'd consider medicating with Kanaplex as well, since the regression is so close to the body. Once it turns into body rot, the chance of the fish pulling through are much lower.

You may need to treat them with Levamisole or Fluebendazole for wasting disease. It is somewhat common in livebearers.