Woke up this morning and my betta died after only 3 months. This is the fourth one in a row now to die in within 4 months of having it. First betta I had lasted almost 2 years in a little bowl and then a 1.5 gallon tank, and part of my reason for wanting the bigger tank was as a big betta tank really. This is annoying me because they're my favorite fish but they keep dying on me without any sign of an issue.
Anyway, not sure on actual water parameters but nothing's changed in the tank for a while now, 78 degrees, been following my regular water changes, he hadn't looked sick or stressed or anything, just the past few days seemed to have gotten a bit lethargic and was hiding and sleeping more than he'd been, but still eating normally and swimming around fine, then turned the lights on to feed them this morning and saw him dead on the bottom of the tank. I'm going to bring a sample of water to petco to get it tested just to be sure everything's fine, but I did a waterchange just yesterday. There was him, 3 platies, 2 danios.
Last one I had before him died without warning too, just fine one day then dead the next. I'd just like to know if anyone can think of any reason why they're dying like this, because I'd like to get another but not if he's just going to die too.
I wouldn't recommend having five other fish in a 1.5 gallon tank with your betta, either. That's just bad news for your ammonia (among other things), and in such conditions you'd have to be doing at least one large water change a day. I'm not sure, but maybe ammonia poisoning may have played a part in your betta's death. Lethargy is a symptom, and a spike must've happened with that many fish.
Yes, the 1.5 gallon shouldn't house anything more than just the one betta. You have problems not only with the ammonia build-up in that small of a space, but the likelihood of maintaining anywhere near the necessary amount of oxygen-diffusion in so little water surface area is pretty much impossible.
Danios and platies need about a minimum of a 10-15 gallon aquarium.
5 other fish in a 1.5 gallon is way too overcrowded. I suggest removing all of them, and letting the betta have the 1.5 gallon to himself. Adding anything will overcrowd the tank and spike the ammonia.
Did you have a heater in the tank to keep the water a steady temperature? Temperature flucuations can cause health problems, and too big of a spike can be deadly.
Also, stress from overcrowding could've played a role in the fish dying. They're territorial fish, and having to share a small space with 5 other fish will definitely stress it out.
Did you have a filter in the tank? How often were you doing water changes?
Oh no no no. The first betta I got a few years ago my mom got with one of those little half gallon betta bowls. After a few months I got him the 1.5 gallon, for himself only. He lived on about another year, then I got another one who was suicidal, then I got a 16gallon tank which is where all the other fish are, the 1.5 gallon I use to store water while the conditioner is working for water changes.
Water changes I do every 5 days, 1.5 gallon so almost 10%, use water conditioner. Have a filter and heater.
And got back with the results, they said there was no nitrates or ammonia, but that the nitrates were a little bit high, I think she said 60 something whatever the thing is. Could that have been it?
Although another thing I thought, I have some decorations in there, particularly a temple thing where he liked to hide, I'm guessing the water doesn't move much in there, maybe an ammonia spike happened just in there and he got sick? Any symptoms of ammonia poisoning other than lethargy?
Try testing your tap water. Sometimes there is stuff straight from the tap water that simply isn't healthy for him. For example, 60 is way... too high. Perhaps there's an abnormal amount of nitrates in your water.
Nitrate levels of 60 parts per million can indeed be quite toxic. I suggest increasing your water changing to at least 50% per week. I recommend two 25% changes every 3 days or so over one really large change, myself...but that's just the way I prefer to do it to maintain a relatively stable water quality.
Are you using any chemicals to prevent algae from growing? I would think levels like that would lead to an algae bloom before a toxic death cloud. You may want to consider keeping some live plants, as the nitrates will be nutrients to them, and you'll have less build-up.
Primarily, though, your problem is water quality. More frequent/voluminous water changes is the quickest fix available.