Ich causing fin loss? Did I make a mistake in treatment?

[SpitFish]

So. I did a stupid thing and introduced ich via neon tetras into my established 30 gallon tank. All 10 tetras died the day after I got them and I noticed the disease then. I also lost a pleco yesterday.

I've been treating the tank with a store bought medicine called API Super Ich Cure. It said remove the activated carbon from the filter, so I removed the filter pad because I couldn't remove the carbon separately, was that wrong? Add 1 tsp per 5 gallons, which I did, wait 48 hours and add it again, did that, wait 48 hours, do a 25% water change and add fresh carbon.

My issue though, is that the fish remaining seem to be loosing pieces of their fins and nothing I've read (maybe I'm looking in the wrong place) says that is a result of ich. My poor dwarf gourami has lost its feelers, one of them has split towards the end and I don't understand why or how to help. The plecos also seem to be losing pieces of their fins but they don't want to move so I can't grab a picture.

As of now my tank is left with 2 common plecos, my male dwarf gourami and 2 mystery snails.

Side note, I do plan on upgrading the size of the tank but won't do so until the disease is completely gone.

I've done 2 doses of the medicine and a 25% water change according to the bottle. The gourami and plecos stay at the top of the water right now and all seem to be experiencing this fin loss. Is this normal or am I having a separate issue?

I'm at a loss and honestly I feel like I may be doing everything wrong. I don't have a heater I can set to a higher temp, it stays right at 76 F. The water parameters are this:

Ph: 8.0
Ammonia: 0- 0.25 ppm
Nitrite: 0 ppm
Nitrate: 0 ppm
GH: 100-200 ppm

I've had the tank for 2 years with the gourami and plecos. The snails were added maybe 2 months ago and the tetras this past saturday.

The ph of my tap water is high, and I'm afraid adding ph decreaser will react bad with the medication? I've of course conditioned all water before putting any in the tank though, maybe I'm overthinking it?

I'd appreciate any help as I just feel like a bad fish parent at this point.
There's a pic of the gourami, his name is Crabcake. You can see where the feeler seems to have split.

 

[FishGuest5123]

What are your water parameters?

 

[SpitFish]

Ph: 8.0
Ammonia: 0- 0.25 ppm
Nitrite: 0 ppm
Nitrate: 0 ppm
GH: 100-200 ppm

I wasnt sure if I can add ph decrease or not because of the medication.

 

[FishGuest5123]

Well, water is fine then. Let’s get some Gourami keepers on here. Are you sure it is ich?​

 

[SpitFish]

Yes, the spots were very visible on the black plecos and seem to have gone away with the medication. I'm not sure the fin damage is a result of the ich though.

 

[FishGuest5123]

It shouldn’t be. Fin damage is usually due to poor water quality but that’s not your case. If it’s more tails that are damaged then it could be nipping.

 

[Jan Cavalieri]

Kind of looks like he's been beat up. This species of Gourami is very beautiful and very passive. I actually had a couple little zebra danio's attack one just like this - just over one day and nipped all his fins. (later they killed all their schoolmates and I moved them out of the tank). I'd be surprised a tetra is doing this but then I was shocked a danio could do this. He's been with the plecos long enough you'd think they'd all get along. Do you see episodes of aggression towards this fish from any other fish? (he is probably the most passive fish in the tank and won't defend himself unfortunately)

If it is aggression you either have to move him to a different tank, or move the aggressive fish to another tank. If you have one particular fish that is seriously attacking and hard nipping multiple fish then I would humanely euthanize it - nobody will want this fish in their tank and you'll risk the lives of all your other fish - it's just not worth it.

 

[SpitFish]

The plecos also have the fin loss, I've watched the tank off and on for a few hours today and nobody seems to be aggressive to anyone else, the plecos stick to the glass towards the top and the gourami swims around a little more than he was doing, also at the top. I really don't understand what could be causing it but I'll keep watching for aggressive behavior or anything else that could be causing it.