What’s wrong?

[FishMom23]

Hello!

This weekend I started noticing these spots on my female Molly, and they seem to be getting worse. Do you have any ideas what it might be and how to treat it?

I currently have her with what I thought was another female (but as of this weekend think may, in fact, be a late-blooming male) in a small (5g) tank. The tank is fully cycled, and we’ve had them for about three months. I do a 50% water change conditioned with Seachem Prime once a week to keep the nitrates low.

I do realize the tank is too small for them but don’t currently have the ability to upsize the tank so am trying to make them as happy and comfortable as possible until I can. I also know that it’s generally better to keep Molly fish in larger groups, but because of our small tank I hadn’t. When I thought we had two females, I thought they’d be alright just the two of them, but now that the other fish seems to be male I’m less sure.

I’m wondering if the male is causing problems. I’m fairly certain she’s heavily pregnant, and just recently I’ve noticed him picking on her more. Could this be wounds from him picking on her? Since I got the tank cycled they’ve seemed content and gotten along really well until recently.

If these are disease spots, how should I treat them? If wounds, would I be better to get a second female for the tank or to keep just the two since I can’t get a bigger tank just yet?

 

[FishMom23]

Note: I’m talking about the two large whitish spots on her body. The other spots are her coloration and have always been there.

 

[FishMom23]

Here is a picture of my other fish when I first got it (top) vs now (bottom).

 

[Colin_T]

It's a bit hard to tell from the angle and more pictures might offer more info but it looks like excess mucous. The fish might have scratched herself and extra mucous is covering the area. Assuming the tank is clean and has good water quality, I would add some salt and see how she goes. If there's no improvement after a week with salt, post more pictures.

The other molly is a male.

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SALT
You can add rock salt (often sold as aquarium salt), swimming pool salt, or any non iodised salt (sodium chloride) to the aquarium at the dose rate of 1 heaped tablespoon per 20 litres of water. If there is no improvement after 48 hours you can double that dose rate so there is 2 heaped tablespoons of salt per 20 litres.

Keep the salt level like this for at least 2 weeks but no longer than 4 weeks otherwise kidney damage can occur. Kidney damage is more likely to occur in fish from soft water (tetras, Corydoras, angelfish, Bettas & gouramis, loaches) that are exposed to high levels of salt for an extended period of time, and is not an issue with livebearers, rainbowfish or other salt tolerant species.

The salt will not affect the beneficial filter bacteria, fish, plants, shrimp or snails.

After you use salt and the fish have recovered, you do a 10% water change each day for a week using only fresh water that has been dechlorinated. Then do a 20% water change each day for a week. Then you can do bigger water changes after that. This dilutes the salt out of the tank slowly so it doesn't harm the fish.

If you do water changes while using salt, you need to treat the new water with salt before adding it to the tank. This will keep the salt level stable in the tank and minimise stress on the fish.

When you first add salt, add the salt to a small bucket of tank water and dissolve the salt. Then slowly pour the salt water into the tank near the filter outlet. Add the salt over a couple of minutes.