vertical spot on side of flag fish. Please advise

[KittenFishMom]

Water parms 

Temp 78f

Nirates 25 ppm

Nitrites 0 ppm

Hardness very soft

buffer (KH) 0

pH very low (yellow, below peach at 6.4pH)

cats have hidden my ammonia strips. 

My Mom has been very ill and I have not been able to care for my fish much since the end of February. We try to get one of us here every 2 to 3 days.

This 10 gallon tank is heavily planted with my best plants and has 4 medium sponge filters going a heater and lights on timers. 12 hours on 12  hours off. I add a wonder shell when I notice they are gone. the other fish in the tank are neons tetras and guppies. all very much smaller than the flag fish.

I have been feeding lightly and hoping for the best. Several days ago I noticed a white vertical spot on the side of my lone flag fish. This visit, the spot is bigger and pink in the middle.

I have included a photo low. I took 5, but none turned out well.

I can't stay with the fish, so treating will be tricky at best.

I can keep the flag fish in this tank and monitor its progress

I can try to treat the fish in the tank, with all the other fish.

I can put the flag fish in my first attempt at a mini pond outside. The mini pond is full of willow and honey suckle branches and green water and daphnia and mosquito lava. The outside temp is going to drop with highs in upper 60's and and the lows in the upper 40's. Lots of great food, but stressful temps.

I do not have a tank I can put the flag fish in at this time.

Please give me your best guess as to what this might be and what would be the best plan of action given my very limited time and options at this point.

 

Thanks so much!!

 

[Colu]

Could be ammonia burn or bacterial infection what you could do is add maracyn and leave it to marinate for a week and add a small amount of aquarium salt 1 table spoon for 5 gallons with your time constraint I think this would be the best course of treatment @Fish Folkkeeps flag fish so maybe he could give you more information on their suitability for ponds 

[Fish Folk]

Agree with @Colu, whatever the initial issue, this looks like it is headed towards bacterial infection. You need anti biotic, and clean water.

Where are you located? 40°s overnight is pretty low. Can you figure out what garden zone you’re in? If in US, then this map can help…

I’m in Zone 6 - western MD. “Safe” date for outside water gardening begins in June. I cheat and start a week or two early. That does sound like a good option.

BTW: she’s a gal 👍

[KittenFishMom]

I'm in Centrally isolated central NY number 5 blue. 

@Fish Folk Which option is the good option? Putting the flag fish in the pond or treating the whole tank? either way, Thanks.

[Fish Folk]

At this time, antibiotics for that tank would be best, but _only_ as specified on the instructions.

[KittenFishMom]

I did about a 40% water change. I dissolved 2 tablespoon of aquarium salt in the last gallon of bottled spring water I added (I waited until it was all dissolved). I added one packet of Maracyn (The amount they want you to add for 1 day for a 10 gallon tank) and 4 almond leaves. I am spending the night at the cottage, so I will add more leaves in the morning. (Still using bottled spring water because I don't trust the well.)

Crossing my fins and hoping for the best.