Should I be concerned?


New Member
Jan 23, 2020
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Costa Mesa CA
Hello everyone, I'm new to the forum and fishkeeping in general. I got this guy about a week ago from petsmart and kept him in a bowl until I could get a tank and move him in (which i did yesterday). But under the light of the tank I noticed this white mark on his side. I am wondering if this is something to be concerned with. I know he also has some early signs of fin rot (I picked up some medicine today for it) does anyone know what this mark on the side could be?



Fish Fanatic
Tank of the Month!
Jan 18, 2020
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Not 100% about the white mark, but it does sort of look like he is missing some scales to me. I personally would hold off on the medication for his finrot and try doing daily water changes first. About 40% - 50% to keep the water pristine. Having clean water will help his fins to heal and also help heal the missing scale - if that is what it is and if it was caused by an injury (as opposed to an underlying disease) - Fin rot is normally an indication of water quality. Some of my bettas have come with mild fin rot due to the conditions they were kept in at the store unfortunately! If it is due to a water quality issue, I have found with most of my bettas they have healed by themselves. I only have used medications if that doesn't work and the fin rot gets worse.


Jan 26, 2008
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Perth, WA
as mentioned above, just do big daily water changes and gravel clean the substrate.
make sure new water is free of chlorine/ chloramine before it's added to the tank.

You can add rock salt (often sold as aquarium salt), sea salt or swimming pool salt to the aquarium at the dose rate of 2 heaped tablespoon per 20 litres of water.

If you only have livebearers (guppies, platies, swordtails, mollies), goldfish or rainbowfish in the tank you can double that dose rate, so you would add 4 heaped tablespoons 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, 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 but the higher dose rate will affect some plants. The lower dose rate will not affect plants.

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.


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