Red Tail Shark, white spots on gills

[robertiv]

Hi all,

As described in the subject, I have a Red Tail Shark with a couple white spots/patches on his gills - left side only. I'd noticed a little white coloration a month or so ago but it was faint then, much more noticeable now.

This is a 38g community live planted tank. I'm a beginner to the hobby but have had this tank since April, so far with pretty good results. Only two fish casualties have been a danio (croaked without warning a few months ago, the rest seem fine) and a flame dwarf gourami who developed a large white spot on one side of his face (between eye/mouth & gills) which then seemed to abscess, he was obviously ailing so I euthanized him. That happened only a few weeks ago.

Parameters as of today are:
Ammonia: 0 - .25 ppm
Nitrite: 0 ppm
Nitrate: 20 ppm
pH: 7.8
KH: approx 80 ppm
GH: 100-120 ppm

I do a 50-60% water change every 7-10 days, which includes light suction vacuuming of the substrate (although I haven't done a full deep cleaning of it). Alternately feed them flakes & sinking pellets, plus occasional fresh veggies.

I've noticed no other patches on the shark. He is behaving normally, eating, etc, but I'm definitely concerned. He's one of my favorite fish. Here's a picture of him chowing down on some kale, showing the spots - sorry for the quality, I really struggle to take good tank photos w/my phone.

Any advice?

 

[Colin_T]

It's either excess mucous or fungus.
Is the fish rubbing on any objects?

 

[robertiv]

Thanks for the reply.

And no - I haven't noticed any rubbing, although he's pretty shy & stays under cover a lot of the time so it's no guarantee.

What level of concern should I have about either of those causes? Any other advice?

 

[Colin_T]

If the fish is rubbing on objects in the tank it is usually an external protozoan infection but it does not appear to have that.

Excess mucous is normally caused by poor water quality. Doing big regular water changes and gravel cleaning the substrate will help with this.

If it's fungus it can spread but healthy fish normally fight off minor infections. Again, big regular water changes and gravel cleaning the substrate can help. You can also add salt.

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You can add rock salt (often sold as aquarium salt), sea salt or swimming pool salt 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.

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 2 heaped tablespoons per 20 litres and if there is no improvement after 48 hours, then increase it so there is a total of 4 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, 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.