Small hole on dorsal fin.... would be pH?

Then, today I perceived a small hole on my lovely betta's dorsal fin, as you can see below:



This is the setup:
• Size: 15.74" length x 11.81" height x 9.84" width, 7.29 gallons;
• Substrate: 11.02 lbs gravel nº 0 (Aqua Pedras);
• Heating: Roxin® HT-1300/Q3 50 W, adjusted to 26 ºC;
• Filtration: Sponge filter Xynyou® xy-2835 with air pump Tetra® Whisper The Shape of Silence™ (10-30 gallons);
• Lighting: LED 4.8 W, 12 volts, 7.87" length;
• Photoperiod: 11 hours daily (10 h – 21 h), with Coibeu YTS-823 timer;
• Fauna: Betta splendens;
• Flora: Elodea sp., Ceratophyllum demersum, Taxiphyllum barbieri and Salvinia minima;
• Other organisms: Cyanobacteria and something else;
• pH: 7.5 (maybe higher than 7.5, since my test limit is up to 7.5);
• Ammonia/nitrite: 0/0 ppm;
• Maintenance: partial water change every two weeks (20 %);
• Feeding: Poytara Betta (Monday to Thursday)[1], fasting on Friday, and live Artemia franciscana (my small culture) on weekends;

What could be this? Well, I'm trying to lower the pH with almond/chestnut leaves, without any success. My tank's cycled since last month.

Thanks for your attention!

Note:
[1] Okay, probably you don't know this fish food (I suppose that is not exported from Brazil) but I may help you with the first ingredients: fish meal (tuna and sardine), salmon meal, squid meal, brine shrimp meal, and flaxseed meal. Guarantee levels are 35 % for crude protein, 6 % for crude fat, and 2.5 % for fiber.

Knowing what your water hardness is will help, Betta need soft water to thrive. I suggest you do big water changes every day rather than every 2 weeks, fin rot is usually down to poor water quality, fresh clean water is the best cure. When his fins are healed you can cut back to a nice big water change one a week.

I would get that cyanobacteria out of there too, that won't be helping matters!

And he really is a lovely Betta

What percent should I use for daily water changes?

How could the cyanobacteria be eliminated?

Should I change anything related to the feeding or not, such as giving more live food to maybe help with recovery?

What are the food directions? Maybe I'm overfeeding him, also, with betta food and artemias.

I'll try to remove detritus with the siphon since I fear removing also the sand... since ammonia and nitrite and zero, the poor water quality would be related to organic matter excess?

You can siphon out the cyanobacteria with your water changes, it will take some of the sand with it but you can always add more. Doing frequent, big water changes will dilute those excess nutrients and muck that the cyano is feeding on. So start with that and see how you go

Hello. That hole is way too small to be a problem. I can barely see it. If you've been an excellent water keeper by removing and replacing most of the tank water every few days, you have a healthy tank and a healthy fish. Its immune system is strong as a result of all the great care the fish receives. If I've just described you, your fish is fine and you have nothing to worry about.

10 Tanks (Now 11)

I saw some cases where people killed cyanobacteria with azithromycin. It makes sense to use this or not?

A few days ago, I also placed a curtain on the window door on that's side of the aquarium, then this should help with something.

Today I made a partial water change and removed ... well, the smell is probably from these cyanobacteria.

Today I recorded another video:

The water became less turbid, also improving even the illumination (yes, I'm using a simple desk lighting yet... with an old fluorescent lamp):

I've never used chemicals to kill cyanobacteria, @Essjay may be able to help you there as she's the chemist around here.

Do you use a hose to change the water? If you don't I would suggest you do. That way you can be precise about siphoning out the CB, it will come off in big sheets. If it was me, I think I would strip the tank and start again after giving it a good cleaning! You've got low flow, a lot of detritus build up and not enough plants to use up the excess nutrients plus a fairly bright light....all things CB love.

Put some black tape over part of your light to dim it a little if you can't change it, and cut down the lighting period to 8 hrs. You need to do bigger water changes, at least 50% to get rid of all the mess that's gathering on substrate and you've got to do them more often than once every 2 weeks. Most people do water changes at least once a week to keep Nitrates to a minimum.

Adding more live plants will help to keep the cyanobacteria at bay as they will outcompete for the nutrients but its photosynthetic so reducing the light is whats going to help the most in that regard

I have to confess I have no idea how to kill cyanobacteria as I've been lucky enough that I've never had it.

My siphon is like this:


I'm in fishkeeping since 2012 and this is the first time I got cyanobacteria in any tank.

I don't see any sense in cleaning all to start another new tank, even more, since it took more than one month to cycle and here in Brazil there's not any good biological accelerator. When I had phytoplankton bloom, many people also said that I should do more partial water changes and I even did anything close to starting a new tank (although don't crash the biological filtration)... after a few times, the issue returned. So I decided to don't do anything and the phytoplankton bloom disappeared after a few weeks. This, however, didn't mean that phytoplankton is the same as cyanobacteria nor that this issue is exactly the same. My main worry is my betta's hole on the dorsal fin.

Since cyanobacteria are... bacteria, probably only antibiotics should kill them and I don't know if this will also ruin my biological filtration.

Anyway, I'll find out if I can buy more aquarium plants to help with the issue.

You can kill the cyanobacteria with meds if you choose, however it will keep coming back if you don't resolve the issues in your tank that are causing it in the first place.

Bigger and more frequent water changes as well as stirring up the substrate to get all that gunk out, and reducing the lighting significantly.

The pinhole in your Betta's fin could be the beginnings of fin rot, which as you know from your 11 years experience as a fishkeeper, is usually caused by poor water quality. I can help you no more, my friend...

Lanpenn said:

I saw some cases where people killed cyanobacteria with azithromycin. It makes sense to use this or not?

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No, absolutely never. Using an antibiotic to deal with a light/nutrient issue (as cyanobacteria is, like problem algae too) is unwise. Antibiotics with fish should, like humans and any animal/pet, be used only for a specific bacterial issue. Any substance added to the water will affect fish to some degree, they are best avoided.

Cyanobacteria is caused by high organics (nutrients) in the presence of light. Reducing light either intensity or duration is not really the answer if the organics/nutrients are not brought under control. One betta is not a waste factory, so feed less, water change more volume, and do a good vacuum of the substrate when you do the W/C, plus keep the filter clean. All the brown gunk is organic matter.

I had cyano in one tank twice, and I dealt with it my siphoning out as much as I could at each water change. If you loosen it with a scraper or your hand, it will fall to the substrate and can easily be sucked out. I also went off the liquid plant fertilizer to force the plants into using more of the natural nutrients. It took a few weeks, but each week there was significantly less until it was gone.

Byron said:

No, absolutely never. Using an antibiotic to deal with a light/nutrient issue (as cyanobacteria is, like problem algae too) is unwise. Antibiotics with fish should, like humans and any animal/pet, be used only for a specific bacterial issue. Any substance added to the water will affect fish to some degree, they are best avoided.

Cyanobacteria is caused by high organics (nutrients) in the presence of light. Reducing light either intensity or duration is not really the answer if the organics/nutrients are not brought under control. One betta is not a waste factory, so feed less, water change more volume, and do a good vacuum of the substrate when you do the W/C, plus keep the filter clean. All the brown gunk is organic matter.

I had cyano in one tank twice, and I dealt with it my siphoning out as much as I could at each water change. If you loosen it with a scraper or your hand, it will fall to the substrate and can easily be sucked out. I also went off the liquid plant fertilizer to force the plants into using more of the natural nutrients. It took a few weeks, but each week there was significantly less until it was gone.

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How much do I feed my betta? Is possible to estimate, including for live food? Live food I give artemias and tiny BSFL.

Lanpenn said:

How much do I feed my betta? Is possible to estimate, including for live food? Live food I give artemias and tiny BSFL.

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The betta members can advise on quality of foods, I will just say that one or two quality flakes or a pellet are sufficient per day, and it does no harm to skip a day or two each week. Fish do not need a lot of energy from food, they don't use it like endotherms, fish being ectotherms. And we provide food without them having to spend energy hunting for it.

For some reason, the hole on my betta's dorsal fin simply disappeared.


Besides this, I reduced the photoperiod to 7 hours a day, also adding more plants (Ceratophyllum demersum, previously treated with potassium permanganate), as well as removing the cyanobacteria from rocks and the dry leaves, where organic matter was also accumulating.

I should do another partial water change today, removing the remaining cyanobacteria that are growing on my plants at least.