Bacterial gill infection, sorority. Advice requested

[Prosper25]

Hey! I have a 29-gallon tank with 5 female bettas, two cherry barbs, an assassin snail, and a young common pleco (still small enough for the tank, don't worry). Two of the female bettas are acting lethargic, resting near the top, not eating, and one displays visibly red gills. How this could've happened is confusing, as the tank received a full breakdown about three weeks ago.

Unfortunately, a couple of weeks ago, not long after the breakdown, I lost one of my females. Looking back, her symptoms/behavior were almost the exact same as the two currently unwell. Treatment (melafix, stress coat, separation) couldn't save her.

Only now have I managed to determine the issue, as their very generic symptoms made researching the specific problem very difficult.

Last night I dosed the tank with melafix. In hindsight, some further research suggested this may not help or could even worsen matters. I'm looking to purchase a treatment that specifically treats the problem (likely API fin and body cure.)

Main questions/need advice:
1: Will the melafix worsen the situation or have zero effect?
2: I just set up a hospital tank, 5 gallons. All new water, treated with stresscoat but not Melafix. Should I proceed in moving the two females here, or should I treat the entire tank? Everyone else is acting normal/showing no signs of illness, but I believe this is contagious.
3: Likely treatment is API fin & body cure. Will this negatively affect the assassin snail or other fish? No live plants in the tank.

29-gallon information.
Nitrite and ammonia both zero. Will post other test results shortly.
Tank is heated, 79.5 F.
It has a UV light, but was unplugged last night when I put in the melafix.
Lots of fake plants and hiding spots.
Filteration: Sponge filter and under-gravel filtration. No activated carbon.
No new fish or objects in over six weeks. Did a full breakdown around 3 weeks ago. 90%+ new, treated water.
Diet is pellets and flakes. They also sometimes get bloodworms.

 

[Andy Sager]

Inflamed gills can be caused by a couple of things. Gill flukes, Ammonia burns, Nitrite poisoning, bacterial infection and fighting are the most common causes.
Melafix is not recommended to use with Bettas due to their labyrinth organ. If the fish already had red gills, that wasn't the cause but if they have developed the red gills since treating with the Melafix, you need to get the fish out of that water and into clean water and hope that the condition is not too drastic. Unfortunately, Bettas are special fish like the gourami family as well or any other fish that has a labyrinth organ. Medications that contain oils or coatings can coat the organ and make the fish unable to extract enough oxygen, from the water or air, and it's downhill from there. When you need to treat Bettas, it's best done in a separate hospital tank with medications specific to fish with Labyrinth organs or that contain no oils or coatings. Since you treated the whole tank, I'd remove all your Bettas to the hospital tank and do not treat with any medications. You need to let the fish try and clean out whatever oils might still be in them. Sadly, it's a 50/50 chance that they will not survive the treatment. What's amazing about Bettas is they seem to be built for healing with just clean water so unless you have a specific diagnosis that requires a medication, clean water alone may solve their problem.

Now to the big issues:
Why did you do a total breakdown?
Undergravel filters had a great run but were found to be one of the least effective filters because what was happening is that detritus and mulm were collecting under the filter plate and that needs to be cleaned out frequently. If you don't remove it, it helps create a food source for eventual higher nitrates which will cause a low pH which can be a problem for some fish species. The sponge filter alone is a better filtering system for your fish so if the opportunity arises, I'd remove the UG filter plate after you've siphoned out what's under it.

Betta sororities: While they are a possibility in theory, Bettas have been bred over the years for fighting and most recently for colors and it's the brighter colors that can be a signal for females to fight the other fish. So just because they are females, it doesn't guarantee that they will get along with each other. The Best sororities are sisters from a single spawn that have never been away from each other more so than individual females that were introduced to the tank at the same time. They are also more successful in much larger and longer tanks. A 29 is only 30" long so not really a very large area. If the fish do survive this episode, you may not be able to put them back together so be prepared for that.

Because you say you had issues not long after the tank breakdown, the almost all new water may have caused the fish too much stress and these fish may have just taken longer to show the symptoms OR they are now showing the effects of the initial treatment with the melafix. At this point, it's hard to say 100%.

Did you quarantine these fish when you got them? If so, for how long?

So for now, the best you can do is place the fish in the hospital tank with the untreated water ( stresscoat is not a medication) and observe and hope for the best. Keep an eye out for ick or other parasites that stress may have activated. If you can post a pic or two of these fish, maybe we can see something on them that you are missing.

Hope this help.