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>> Such hubris, I was posting about adding fish, and now one has died. Just got back from the GH, found one of the big talapia floating on it's side in the tank, stiff and dead!

>> No pictures, but much of the fins were only cartilage, the dorsal fin (top fin) was about half cartilage and half covered with cartilage exposed above the tissue, the tail-fin was also half gone the same way, and the propelling fins (near the gills) were all cartilage, no flesh or tissue. Mouth was without sores or lesions, belly was lesion free as well, but near the tail were three open lesions, pale and almost circular perhaps the size of a dime (on a fish that was almost 12 inches long tail-fin to mouth). Each of the lesions was surrounded by a slightly elevated (1mm) white ring, a total of three, two on one side and one on the other; all three were right up against the tail. On one it was possible to see the exposed tendon that runs mid-line on the side to the tail.

>> There was no loose tissue or ichy stuff. The scales looked to be intact except at the tail. I have been feeding the fish every day, and the bottom of the tank is clean, no deposits of food or fish waste. No algae in the tank that I can see. Fish tank temp varies from 69 to 76 depending on days when the supplemental heat is on.

>> I have supplemented with potassium bicarbonate to adjust the pH from 6.0 to approximately 6.8. The potassium bicarbonate is used in wine-making and was added as a solution into the sump tank at a rate of one/quarter cup per 250 gallons, per day. It was added about every third day when the pH dropped to 6.0.

>> Looking down through the water at the other fish, they look OK, but I would have said the same about this fish as well, yesterday. Any ideas of what it is and how to treat it? There are 3 other big fish, and maybe 25-30 smaller tilapia and 4 mid-sized gold-fish. I actually expected the small fish to die first, if any were to die, as they seemed to have the least internal resources.

>> Any help would be appreciated. Ask questions, I will answer. I do want my fish to live.

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Replies to This Discussion

Do you test for kH and gH?  I don't know if it's possible to get too high a reading on carbon hardness.  If I were adding potassium bicarbonate it would be to raise my carbonates.

No idea needed to test. I have ordered the testing kits. Any other things to test for do you think?

I was thinking adding a little potassium for the plants, the K in NPK (fertilizer ratios) [nitrate, phosphorus, potassium].

Try adding crushed oyster shells to your bed. They give off a very slow bicarbonate release over. . decades.

I don't know your system, but most of the damage (besides the lesions) would be from post mortem picking by other fish. Some fish will just get infections, this doesn't foretell a system wide failure.

Jon Parr told me to hang a bag of oyster shell to (2 cups) in my fish tank.  He said it will overtime stabilize the system
Brady A said:

Try adding crushed oyster shells to your bed. They give off a very slow bicarbonate release over. . decades.

I don't know your system, but most of the damage (besides the lesions) would be from post mortem picking by other fish. Some fish will just get infections, this doesn't foretell a system wide failure.

Thanks both of you, Brady and Linda. Looks like I'll have an oyster snack tomorrow.

Linda did you break the shells or did you leave them whole? Hanging them in my sump tank was what I was thinking, that way if I get too high a pH I can reduce the number of shells, and if I don't get what I need I can add more. What did you use as a bag, old pantyhose, a lingerie wash bag?

I don't want to add them to the growbeds, as they are not so easy to get out, if that is the need.

Brady A said:

Try adding crushed oyster shells to your bed. They give off a very slow bicarbonate release over. . decades.

I don't know your system, but most of the damage (besides the lesions) would be from post mortem picking by other fish. Some fish will just get infections, this doesn't foretell a system wide failure.

The benefit of a buffer such as a bicarbonate is that you can't over-do it. It is a buffer, which means it stabilizes around neutral pH.  You can't "over-do" this type of addition to your tank.  Oyster shells are a very slow leach of bicarbonate.  Look at them as a long term response to the acid creep.

>> 3 days later, no dead fish, no sick fish, all have fins and are swimming vigorously in the tank. Food is eaten and none left behind. Goldfish are noticeably bigger than on arrival. Some of the small-mid sized fish now appear bigger. gH in house is 4 drops (50-100 ppm) and in tank is 2 drops (0-50 ppm). kH is the same 4 drops in the house (50-100 ppm) and in the tank 2 drops (0-50 ppm). Tilapia and Goldfish can handle much higher gH and kH than these, but adding bicarbonate at this time does not seem advisable as pH is around 7.8. Bicarbonates would just raise the pH to make it even more basic.

>> Oyster shells: I had a nice snack of 12 oysters and then boiled the shells to denature the proteins and make it easy to push off the anchors that the oysters left inside the shells.  I then let them air dry, and put them in one leg of an old pair of pantyhose and tied the other leg onto a support and dropped them into the sump tank. Today the pH is 7.8 up from 6.4 the day before. Hmm, I hope they find some balance.

If you want to lower your pH, you could fill 5 gallon bucket from sump and add HCL to lower pH to 6.0. Then add this in some amounts back to sump.  I'd go slow, recheck pH next day and see results.  So over time you could lower by .2 increments to where you are comfortable.

Nice that you have kH in water source.  I don't have any and so I must add it.

Glad to hear about your fish.

Don't worry the Ph will creep down.  It takes a long time for the carbonate to be released from the shells.  The rate of release will vary depending on if they were crushed or not.  I would suggest in the future to get crushed oyster from a feed store, as it is a common supplement for chickens.  Very cheap as well.

>> Thanks, I wouldn't have thought it was so easy to get. I'll look tomorrow.

Brady A said:

Don't worry the Ph will creep down.  It takes a long time for the carbonate to be released from the shells.  The rate of release will vary depending on if they were crushed or not.  I would suggest in the future to get crushed oyster from a feed store, as it is a common supplement for chickens.  Very cheap as well.

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