Can PH Fluctuations Lead to Illnesses in Betta Fish?

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Q: C wrote,

Remember me? I emailed you awhile back about my male fish named Sushi. He had the mysterious disease. He finally had gotten better with the inside/outside anti bacterial food. He was all back to normal. But that only lasted about 3 weeks or so.I have been doing the water changes AND I got the test stripes to test the water regularly. Problem is the PH will NOT come down. Even after fresh changes. I bought the PH DOWN. It does NOT help. I did it in stages, so it would not stress him out. It says on the bottle that some tap waters are so resistant to the PH down that it may not work. I checked it again this morning, and every time it’s HIGH PH. Highest there is, so the alkalinity is also high. Everything else is OK though.

Well, he now has fin rot. He has lost at least 70% or more of his fins! He has a few white dots on him but not all over like ICH does. He is still swimming up top and he eats like a pig but now has the white spots/dots and fin rot. This is NOT the cheese grater white like last time… its actual spots, like salt. But again, only about 5-6 spots only.

What now!!?? I am going nuts? I don’t know what to do about the spots/rot and can’t get the PH down. Suggestions? I appreciate everything and your time!!

A: It’s nice to hear from you but I’m sorry to hear Sushi is not feeling well again. It sounds like there are a few things going on here. First, I believe it is better to deal with a high pH that is stable then mess with changing the pH. The fluctuations can be very dangerous to your fish. PH Down really doesn’t work and could even be a major contributing factor to Sushi’s fin rot and what I believe may be Ich. As you know I also live in southern California and just like you I have very alkaline pH. In fact, I have to buy a HIGH RANGE pH test kit just to get proper results because the regular one doesn’t even go high enough to give me an accurate reading. My tap water (from the faucet) is 8.2. It will often come down a bit, once the water stands for awhile, but the new water from the faucet has a very high pH indeed.

There are a few reasons why pH DOWN doesn’t work. First, the ability for the pH to fluctuate is determined by its buffering capacity or KH. (KH is also called Carbonate Hardness). The KH is what keeps the pH stable. Unless the KH is very low, the pH will just bounce right back to where it was. Making the pH bounce from high to low and back again is extremely dangerous to fish and in some cases has been known to kill off entire aquariums. When this happens, aquarists call this a “pH crash”. Another reason why you can’t keep the PH low is because you are regularly changing your water with new clean water that happens to have a very high pH. Of course you have to continue with regular water changes so may have little choice but to deal with less than perfect pH.

Regarding your white spots, it does sound to me like Ich. Seeing 5 -6 spots could be the early sign. If left untreated the spots (parasites) will fall off and reproduce only to come back as 10-20 spot and then progress from there until your fish is in serious shape. Luckily Ich is easily treatable. I suggest Rid-Ich+ which has always worked great for me personally and can be found at any pet store that carries fish supplies. Ich parasites are common but typically infect stressed fish.

Fin rot, however, is a bacterial infection and occurs most commonly as the result of poor water quality but may be the result of stress. When fin rot progresses to the point of 50% fin loss or more I generally recommend an antibiotic like tetracycline or Maracyn-Two. As always with antibiotics, be sure measure the doses carefully and administer the full course to help avoid antibiotic resistant strains of bacteria. If you decide to treat for both Ich and Fin Rot at the same time, read the packaging on both medications carefully to be sure they are safe to use together.

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1 Comment

  • Josh

    This seemed like a good place to share a recent experience that may be helpful to other readers. I recently moved to Connecticut, which is a densely populated states with lots of cities and townships bumping up against one another, and—more to the point—lots of different municipal water treatment facilities. Around here, it’s extremely common to have a different water provider than a neighbor just a couple miles away. Likewise, it’s highly likely that the fish store down the street has a different water supplier than you do at home. I found this out the hard way and wanted to pass along my experience in the hopes that it will help the next person.
    The problem that I encountered was that the fish store where I purchased my betta used a municipal water supply that was markedly different in pH from my own. While I’ve kept fish for years, I’d never lived in a place where this was the case before—usually the chemistry of my water looked very much like my fish store’s sater—and I thus vastly under-appreciated the importance of pH acclimating my fish.
    I gave the betta some time to temperature adjust before dropping him into his new tank, but I didn’t acclimate him to the pH of his new home. While he looked fine and happy at the time, he had in fact gotten a “pH burn” upon entering his new tank that made him more susceptible to opportunistic infection. I woke up one morning a few days late to find he’d come down with a fungal infection that, in the span of a single night, had covered both his ventral fins, half a pectoral fin, and a portion of his anal fin. He was in bad shape, and listing on the bottom of the tank.
    Since the infection was apparently spreading rapidly, I medicated the tank as soon as possible and began frequent 100% water changes (the tanks is a bit small at 2.5 gallons, so I couldn’t do partials; looking forward to upgrading). The fungus stopped spreading, and since then, he’s perked up. The signs of infection seem to be gone—no more patches of fungus, he’s swimming actively, flaring, and appears back to his old self.
    But despite getting rid of the infection quickly, it had already ravaged the affected fins. He lost both ventrals, a chunk of a pectoral fin, and part of his anal fin. He still has enough finnage left to swim fairly normally, but assuming that my best efforts continue to keep him healthy, it’s still going to take months for him to recover from the damage. I’m glad to have saved my new friend, but I feel horrible to have made such a costly mistake.
    The moral here is to be careful to pH acclimate a new fish. has some nice instructions on how to do this. The gist is that while the betta is still in the water you’ve brought home from the fish store, add a little water at a time from your newly prepared tank to the the fish store water, allowing the fish to gradually adjust to the new pH. Finally, after doing this for awhile, and giving the fish some time to adjust, you can go ahead and temperature-adjust the fish, then finally add her/him to her/his new abode. It’s also advisable, of course, to actually test the difference in pH between the home and fish store water, so you know in advance what kind of pH difference you’re dealing with—especially if your fish store has a different water supply than you do.


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