I got a two gallon tank for my Betta and some fake plants and today the water got cloudy and he's hanging at the bottom of his tank. I'm not sure why he's so down and how the water got do dirty in just two days.
Foggy water is often caused by a bacterial blossom.
On itself it is nothing to worry about, and the water is not actually 'dirty'.
But you need to provide more information to be sure if that's really what's going on here.
You mentioned that the water got so dirty in just 2 days. Does that mean that you set up the tank and immediately added the betta to it?
In that case it is something to worry about, and it is also not healthy for your betta. Which could then also explain the lethargic behaviour.
Before adding fish to an aquarium, it has to go through a 'cycle'.
During this period you need to have your aquarium running with water, filters, heater and lighting. But without any fish. Keep it like this for at least 2-3 weeks.
During this period the chemical composition of the water changes and the growth of these 'good bacteria' start.
In the first week it will get a peak of the levels of ammonia and nitrite. If these values get too high, they are lethal for your fish. Once you get enough of these bacteria, the levels of ammonia and nitrite will disappear. And only then your tank is ready to get some fish.
But it's a bit too late now to cycle your tank.
So what you should do now is:
- Make sure you don't feed the fish too much. Once every 2 days should be ok.
- Do a daily, partial water change. 50% should be ok
- Adding some real plants is also better than plastic (the plastic can also hurt the fins of your betta)
- Get a test kit for ammonia and nitrite. If you measure daily (before changing the water), you should see a spike after about 1 or 2 weeks. If it's back at 0nppm (when it is actually safe to add fish to it) you can stop doing these water changes..