Help with guppy treatment for suspected saprolegnia and columnaris
Hello fish frens, I would like to get some tips on treating my guppers with suspected saprolegnia and columnaris. Long post ahead please bear with me.
I first noticed on Saturday morning (posting Monday evening where I'm from) that one of my females have bulging eye on eye side. Research suggests injury (tbh I was HOPING it was just injury), so I kinda just ignored it and wished it will recover on its own. Until Sunday evening, the "injured" eye seemed bigger and is kinda fluffy. At this point, I had no idea about columnaris nor saprolegnia.
When I checked this morning, I noticed another female guppy with white growth in the mouth and a male with "torn" tail fin around the middle-top part.
I decided I wanted to establish a 7.5 gal hospital "tank" (storage box container), but I don't have methylene blue nor aquarium salt on-hand and the gear for stronger aeration in the HT. I ordered what I think I'll need and they should arrive tomorrow.
This afternoon, I noticed the tail of the infected (is that the right term) male having similar puffy growth on the infected female's eye. I thought it was getting worse and a friend recommended doing salt dips to try to prevent any more complication.
We dipped the 5/6 fishes (last one seemed healthy and kept on running away lol) for around 6 mins tops, let them rest at a small container, then returned them to the main tank. Solution was supposedly 10 tbspn per gallon, but scaled down to work with 192 mL. I did some potentially stupid maths (converted units to mL, set tbspn to 7.5 mL on ratio, and got 192.5 for water volume) scaling the numbers down, so I honestly think I messed up here. The two males seem to be fine, but the remaining females seemed to have... gotten worse.
Two of the females seem to start showing the white growth on their body, while the one with the eye injury accidentally bumped into hornwort, removing the loosely hanging white stuff from the eye and bled a little. I was and am still very much worried; the three of them are hovering near the surface where the air stone's bubble rises. They usually chill is by the RRFs and hornworts.
For context, I have a 20 gal cube with 6 guppies (4F 2M), 3 copper cories, 3 tri cories, and 6 shrampies (though I only ever see 3 at most). I also have 2 guppy fries which seem to doing well. I only have test strips for testing so water parameters are very rough estimations, but ammonia is 0 (Seachem ammonia alert) , 1ppm nitrite (pretty bad), 0-10ppm nitrates, 75 GH, 4 KH, and 7.2pH. API test kit is pretty pricey but am trying to make some space for it.
Tank is 2 week-old, which I think is pretty bad since fish-in cycling and all. Tank is also lightly planted with stem stem plants (4 types I think), amazon sword, and a couple of anubias with a few red root floaters and hornwort.
Tank mates seem to be doing fine; corys are cute as hell and are always very busy while the shrimp are starting to be more show more and more instead of always hiding.
I did a bit of research for treatment and this is what I plan to do: 1 week salt bath with 1 tbspn / 2 gals of salt and whatever is the proper dosage of methylene blue. Planning to increase salt if symptoms persists or worsens. Can anyone please guide a lil noobie fish keeper help their lil guppers recover?
TLDR: planning to treat suspected (my gut says confirmed but my gut has 0 experience with fish stuff, first "proper" tank) columnaris and saprolegnia, tried salt dips, but planning to do salt and methylene blue treatment in a 7.5 gal hospital tank when supplies arrive. What else should I be doing to help my guppies recover?