move the fish to a cup with clean water (bottled water ideal, or if its tap water, let it sit an hour or two to adjust to the room temperature)
then, empty that fish tank using a small bucket or cups of water.. whatever u have to do. then when its light enough to carry, dump the rest of the water outside or in the toilet and wash the tank real good in the tub. u can use bleach if u want, but make sure u rinse it for a full 5 minutes with water to make sure its clean. Any leftover cleaners can kill the fish.
look on amazon or at walmart for a cheap power filter. they are easy to use and work great. example: https://www.amazon.com/Tetra-Whisper-Power-Filter-Three-Stage/dp/B001CHXJSK/
you hang it right on the edge of your tank. it'll replace the built-in filter, and it will work fine with what you have. you'll never have dirty water again and since u only have 1 fish, you'll only have to change the filter floss a couple times a year. make sure you dont overfeed the fish. only feed enough, so that everything is eaten within 5 minutes. if there is food left over after 5 minutes, you are feeding too much
good luck
I had to get this filter set up because it was all they had, but I have the marineland s10 on the way to switch out...unless that will hurt my cycle......
You can get an idea of how much is actually tank based on the gravel at the bottom and where the hang on back filter is (the black tube is the intake. That would generally be about a finger width from the back).
So let's guess how large the tank actually is: A square tank that is 15.8 x 15.2 x 17.6 inch, which are the dimensions of the iMac G3, would only be 18 gallons. However, the shape is more trapezoidal than square and the tank is inside of the case.
For the sake of simplicity lets say the Front is 17'' and it is 15'' tall/15'' deep. The back of the tank looks to be approximately half of the front of the tank so I'll say 9''. The trapezoidal prism would then be 2925 cubic inches, which translates to just over 12 gallons. And this is definitely overestimating because the tank is a good 3 inches shorter than the case of the iMac plus the water level isn't completely full. I'd guess if you were to actually measure you'd be lucky to break 7 gallons of liquid.
EDIT: I replied to this out of my inbox and didn't see someone else in the comments calculated their estimate at about 5.5 gallons.
Heck it doesn't even have to be expensive to be humane, if you don't care how the "tank" looks. She could've bought a 5~10 gallon food grade plastic tub at the dollar store, kept an eye out for cheap/free plant trimmings on the local fish FB groups, and thrown in an old mug or pot for decor. Add in a basic filter and a cheap heater and you barely hit $20.
Which I bet is not much more than she paid for the death trap the poor fish is in right now.
I've been looking at this filter on Amazon: https://www.amazon.com/Tetra-26316-Whisper-Filter-5-10-Gallon/dp/B001CHXJSK
hiya, please remove the affiliate tag from your amazon link (it's the tag= bit), or post a clean link (like this: https://www.amazon.com/Tetra-26316-Whisper-Filter-5-10-Gallon/dp/B001CHXJSK).
Will this be okay?https://www.amazon.com/Tetra-26316-Whisper-Filter-5-10-Gallon/dp/B001CHXJSK/ref=sr_1_3?ie=UTF8&qid=1504055706&sr=8-3&keywords=5+gallon+aquarium+filter Would I need a sponge on the intake for shirmps?