[Jmusgrave7]

If I had to diagnose anything by the photo alone I'd say Columnaris. I lost all my fish a few years ago to Columnaris and I had to start again. I had a break from the hobby because of it, it's devastating. Again, please don't take my diagnosis as gospel, but the speed you're losing fish and the cotton like growths are similar to the symptoms of my fish. Columnaris can wipe out a tank in anything from 24 hours to a few weeks.
Have a look here... Identify and Treat Columnaris (Saddle Back Disease)

I read that article & it says “Straight up, if you see little tufts of cottony stuff that resemble white-colored bread mold, it isn’t columnaris.” But a lot of the other identifying symptoms are there. I went to a fish store (much better then petsmart or petco, etc) yesterday before I saw your response & they recommended Furan. I immediately started treatment but having not read the article yet, I medicated the whole tank! Ugh. I can’t do anything right for these fish. Im pretty sure it’s too late for the poor eel but I feel awful just letting it die without trying help it. If it was you, would you stop medicating? Or would you get the KanaPlex & continue to try? There’s only the eel & 3 orange & black Molly’s left. I’ve spent a lot of time & a lot of money on this tank for it to be completely depleted in less than 2 weeks!! Also, we woke up to a bunch of foam on the water surface so I “closed” something on the filter. I’m not exactly sure what it does but it seems to have slowed the water flow. It’s not as bad as it was earlier, but still foamy. Is this from the medication?

 

[WaterChange]

Yes the foam is from the medication, a lot of meds do this. Make sure you have plenty of aeration in the tank as meds can deplete some of the oxygen. I have to say that I would continue the medication because there are symptoms similar to Columnaris. The position you're in with your tank now I would try anything. I am however assuming you've tried medicating for other issues before now?
See out the treatment and hopefully it will clear up. How are the Mollies health wise?

 

[Jmusgrave7]

Yes the foam is from the medication, a lot of meds do this. Make sure you have plenty of aeration in the tank as meds can deplete some of the oxygen. I have to say that I would continue the medication because there are symptoms similar to Columnaris. The position you're in with your tank now I would try anything. I am however assuming you've tried medicating for other issues before now?
See out the treatment and hopefully it will clear up. How are the Mollies health wise?

The Mollies seem fine. As long as they get fed, nothing seems to bother them! I have a bubbler in there & tons of live plants. Unfortunately, I have not medicated them until now. I wasn’t sure what was causing them to get sick & I was afraid of using the wrong medication & making everything worse. But everything went real bad anyways. Im trying to get the KanaPlex but am having trouble finding it. As far as the water flow from the filter, does it matter if its flowing fast or slow? & lastly, the ammonia is a little high. Should I treat it with something?

 

[WaterChange]

The Mollies seem fine. As long as they get fed, nothing seems to bother them! I have a bubbler in there & tons of live plants. Unfortunately, I have not medicated them until now. I wasn’t sure what was causing them to get sick & I was afraid of using the wrong medication & making everything worse. But everything went real bad anyways. I just went out & got the KanaPlex. Do you think I should wait to add it till after this first treatment of the Furan is done or add it now? As far as the water flow from the filter, does it matter if its flowing fast or slow? & lastly, the ammonia is a little high. Should I treat it with something?

The filter running fast or slow is basically how much water is being turned over in the tank. If your tank is 30 gallons it's recommended to have a filter capable of turning over around 120 gallons per hour.
If the ammonia is high it would have been best to carry out a water change before medicating. It seems as if your tank isn't cycled if you have such few fish and high ammonia. I'm now unsure what to suggest for the best. If you haven't medicated until now I think I'd start from the beginning. Carry out a 75% water change and then carry out a 40 to 50% water change each day for a week and see how the fish react. I would also buy a bottled bacteria and add it straight to your filter. I'm not a huge fan of the stuff and I don't think it does a great deal but I think I would be trying anything right now to get the tank cycled and the fish healthy.
If the fish are still dying after all this I would literally start again. Quarantine any remaining fish and treat them while cleaning the main tank thoroughly.

 

[Jmusgrave7]

The filter running fast or slow is basically how much water is being turned over in the tank. If your tank is 30 gallons it's recommended to have a filter capable of turning over around 120 gallons per hour.
If the ammonia is high it would have been best to carry out a water change before medicating. It seems as if your tank isn't cycled if you have such few fish and high ammonia. I'm now unsure what to suggest for the best. If you haven't medicated until now I think I'd start from the beginning. Carry out a 75% water change and then carry out a 40 to 50% water change each day for a week and see how the fish react. I would also buy a bottled bacteria and add it straight to your filter. I'm not a huge fan of the stuff and I don't think it does a great deal but I think I would be trying anything right now to get the tank cycled and the fish healthy.
If the fish are still dying after all this I would literally start again. Quarantine any remaining fish and treat them while cleaning the main tank thoroughly.

Unfortunately, the eel died last night so we are down to the 3 Mollies. 12 dead fish & 4 dead snails later... starting over seems to be the best option. I really appreciate all the advise you’ve given me & I feel like I’m starting to understand this whole process a little better. I’m going to do a 75% water change tonight & 50% daily for the next week, & treat the water with conditioner & bacteria. But before I started to medicate the other day, I switched the carbonated filter out with filter floss. I put the carbonated filter in a bucket with tank water where it’s been soaking since. Would you recommend leaving the floss in or replacing with the old filter when I do the water change tonight? Thank you so much again for all your help! You have no idea how much I appreciate it! Lastly, I took a few pictures of the eel to share with you. I think you were 100% right when you suggested it could be Columnaris.

This makes me so sad because I know he suffered. If these last 3 Mollies don’t make it, I don’t think I’ll do this again. It’s been really really hard watching all these fish die like this.

 

[WaterChange]

You're very welcome, always happy to help if I can.

Sorry to see the poor little fella like this. It's difficult losing fish when you try to take such good care of them.
I think I would literally start a fresh. Leave everything is it is and carry out your water changes while keeping an eye on the mollies. The problem you have now is the mollies may have the infection and if you put other fish in with them it may happen again. If the mollies show the same signs and you know for sure they are suffering and will die, I would euthanize them. Not pleasant and not something any fishkeeper wants to do, but sometimes it has to be done. Then I would clean the tank and filter thoroughly and start again with new substrate, plants etc.

Again, this is my opinion and others may disagree. It's very difficult when I can't physically see your tank, if you were local I would certainly help you as much as I could. I really hope you get it sorted out soon. A tank you're not enjoying becomes frustrating and a chore rather than a pleasure.

Keep us all updated

 

[Jmusgrave7]

You're very welcome, always happy to help if I can.

Sorry to see the poor little fella like this. It's difficult losing fish when you try to take such good care of them.
I think I would literally start a fresh. Leave everything is it is and carry out your water changes while keeping an eye on the mollies. The problem you have now is the mollies may have the infection and if you put other fish in with them it may happen again. If the mollies show the same signs and you know for sure they are suffering and will die, I would euthanize them. Not pleasant and not something any fishkeeper wants to do, but sometimes it has to be done. Then I would clean the tank and filter thoroughly and start again with new substrate, plants etc.

Again, this is my opinion and others may disagree. It's very difficult when I can't physically see your tank, if you were local I would certainly help you as much as I could. I really hope you get it sorted out soon. A tank you're not enjoying becomes frustrating and a chore rather than a pleasure.

Keep us all updated

Isn’t that the truth!! I should have done my research when my son 1st got the tank... things may have been a little different. We won’t be getting any new fish for awhile. Once the tank is more established & the water conditions are under control, I’m going to do some fish research before hand. Having compatible fish will also make this much easier! I will definitely keep you posted