Fungal or bacterial infection on betta?

[biofish]

Not my fish, so I can’t give exact parameters, they just sent me pics and I wanna confirm with y’all.

I recommend the api em erythromycin bc it looks like a bacterial infection. But it could also equally be a fungus and I’m not sure if that requires a different treatment?

This fish just recovered from a nasty case of fin rot a couple weeks ago, But that’s about where my knowledge ends

 

[Colin_T]

The fins look like that have excess mucous on the edges.

No about about the white patches, need better pictures for that, but I doubt it's bacterial. Bacterial infections are usually red and flush with the skin. The white things look raised.

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Are there any other fish, shrimp, crab,s snails or anything else in the tank?

Find out what sort of filter is on the tank and how often they clean it, and how they clean it.

Get them to check the water quality for ammonia, nitrite, nitrate and pH.

Get them to do a 75% water change and gravel clean the substrate every day for a week.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

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If there's no improvement after a couple of big water changes, add some salt.
Use 1 heaped tablespoon of rock salt (aquarium salt) per 20 litres (5 gallons) of tank water. If there's no improvement after 48 hours, then increase the dose rate so there is a total of 2 heaped tablespoons of salt per 20 litres.
Keep salt in tank for 2 weeks.