fish dying, nothing has changed.

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skoglunc

Aquarium Advice Newbie
Joined
Apr 7, 2020
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I have a 30 gallon freshwater tank, nothing fancy as I wanted low maintenance because it's in my shop. It has blasting rock for substrate, rocks, some live plants, and then for fish it's got cory's, testras, and some algae eaters (about 12 fish); it's pretty basic. It has been up and running for ~ a year and a half and has had the same fish since the beginning. Other than the routine cleaning, filter changes, water swaps, and minor stuff, nothing has changed, and especially nothing in the last few weeks. I went out yesterday and found one of my cory's dead. I was bummed because it's the first fish I've lost on this tank, but I didn't think too much of it since the tank itself hasn't showed any signs of anything going wrong. The rest of the fish are all very active and nothing appears to be off, so I figured it was just this fish' time. Well I went out today and I found another one of my cory's dead...that's 2 cory's in 2 days. Now that starts to make me think something might be going on. I grabbed my PH tester and checked it and it came back at 8.25. I believe that's a little high, but is that high enough to start killing off my fish? I haven't had any problems prior to this so I haven't tested it consistently, so I don't know what it normally is. Looking for direction on where to go. Should I try and start lowering my PH? Or do you think this is just a coincidence? Any direction or advice is appreciated, thank you.
 
I wouldn't mess with pH, as pH is unlikely to be the problem unless it has been swinging, and changing it is likely to further stress your fish. Most fish can deal with a non-optimal pH, as long as it is kept stable.



What are your other parameters--ammonia, nitrites, nitrates? Is your temperature correct and stable? Also, what is your regular maintenance regimen? You mentioned "low maintenance" a couple of times, so it's possible that your maintenance regimen has been insufficient and you are only now reaching a point where there is a problem. Alternatively, you may have done a too-thorough clean recently. Have you recently cleaned out your filter, and did you remove the wet media?



If you can post your actual water parameters here, and also give some idea of your regular and recent maintenance schedule, it might help people here help you to figure out what has gone wrong. I am sorry about your cories.
 
If I suspect something is killing my fish, my first move is always to do a significant water change--50 percent, perhaps even followed by another before too long. Of course, match temp and use dechlor.



The only caveat to that advice is that, if you have a tank that has been long and severely neglected, a major water change could shock the fish, so it would be necessary to do smaller water changes over time. It doesn't sound like this is the case for you, though, since you do mention doing regular water changes as part of your maintenance?
 
Water changes are always helpful and a must. Perhaps your two Corys lived their life expectancy or they had an enemy in the tank you were not aware of? I dont think a ph of 8 +/- is a big deal.
 
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