Bumblebee goby knowledge? Frayed fins?

Female bumblebee goby with frayed tail?

I couldnt get a good photo of the tiny guys but i have 3 bumblebee goby in my guppy community tank. I think 2 male/1 female or 1 male/2 female.. 1 is definitely less colorful and larger but possibly a second as well.

Established aquarium, levels are very consistent, 10% water change a week if that.
Ph 7.2-7.6
Ammonia and nitrite almost always 0 or very low.
Nitrates about 20 average.
Gh & kh are a bit lower than ideal but stays consistent.

40 gal breeder with large canister, planted tank.
3 bumblebee gobys
18-20 guppies
2 corys (dont seem to bother them)
1 sm yoyo loach (temporary home, should i move him?)
And some ghost shrimp

My guppies had some fin/tail rot that ive been giving them paraguard & methylene blue bath/dips for. They seem to be healing well. New fish from AFS came sick.. i thought they were on the uphill but it came back and affected all my guppies.

Is this possibly whats causing tail fraying in my gobies? Should i give them a bath/dip?
Are bumblebees okay for paraguard and blue?? Or could it be that the goby that took over the cave is being nipped over territory, breeding, babies etc??

Theyve never been sick untill now so im trying to figure out whats safe for them. Im fairly new to the gobies.
They eat shrimp cuisine, decapsulated brine shrimp eggs and live brine shrimp. Occassionally munch on algae wafers as well. Theyre all eating well. Pretty active and look well otherwise. The 1 female for sure has taken over a cave system and only comes out for feeding time. She is the one i believe has tail fray?

Any and all info or knowledge on bumblebee gobys would be so appreciated. Educate me

1st photo is what i believe to be female, second is my tiny guy i believe is a male. There is another lighter colored one as well.

 

I would try bigger water changes or more frequent water changes before the meds, personally. Super clean water often does wonders at healing/preventing fin issues and i really hatedealing with meds! But as far as i know, the gobies are fine for those meds.

 

I would try bigger water changes or more frequent water changes before the meds, personally. Super clean water often does wonders at healing/preventing fin issues and i really hatedealing with meds! But as far as i know, the gobies are fine for those meds.

BigManAquatics, my water is extremely acidic here with very low ph so ive tried to get the tank stabilized and remineralize as i change water. So i can only do smaller water changes with my system at the moment. Preparing harder water in smaller quantities. Ive considered doing it more often.. i avoid meds at all costs here. I prefer more freshwater or salt when i can as well. Untill i start losing fish (which happened with alot of guppies)
Hoping to gain some knowledge where i can!!
Your input is appreciated!!

 

With that amount of bio load I’d definitely recommend creating more hard water more frequently as 10% water changes a week probably isn’t cutting it with the nitrates

 

If your water is acidic and soft then guppies and gobies are probably not the ideal species to keep since they prefer hard even brackish water. If I suspected health issues with a bumblebee goby I would consider increasing the salt level but whilst your guppies would be fine with this your corys would not. Basically, you are keeping species that are incompatible with each other and with your tap water.

 

Since the tank is like 90% guppies he could just make this into a very low salinity brackish tank, I don’t think it would be hard to move a few cories and shrimp to a 10 gallon