You should also use test strips to analyze your water parameters in real-time. To help with unfiltered tanks, remove uneaten food and poop before it settles and decays (pro tip: use an aquarium designated turkey baster to easily suck debris out of the tank). After reading the section below, you’ll quickly realize why filtered tanks can be more beneficial for betta fish and easier to maintain.
A Warning About Distilled Water and Betta Fish | Fish Care
I have 3 male Betta (all in separate tanks) General-a dragonscale, Admiral- veiltail and Halo a halfmoon. I have had Admiral for over a year happy as a clam in his tank. However, General has developed something in his tank and it's spread to my 3rd tank(Halo) due to accidental cross contamination :( I have since been a lot more careful in avoiding that. All three of them get their tanks cleaned once a week and I had the water tested when this problem first occurred and the guys (from a tropical fish store) said the water was fine and that the issue was “rotting uneaten food.” However I very much doubt this because I feed only what they will eat – interactive eat this bite and then you can have another – I feed them 3 Betta bites and sometimes blood worms. The dragonscale tank developed a white translucent film over the entire surface of his tank. I can make it go away by carefully pulling all or rather most of it off the top. I've scrubbed his tank and rocks thoroughly many times using extremely hot water. Originally his rocks were also developing a film the first few weeks and I thought that was what was causing it but after a while they are no longer slippery now and the film still develops after each cleaning. All three of them are in glass tanks and only when I got the dragonscale did this start occurring. Never had this problem before, it's not in my 15 gal tanks and wasn't in my *original * Betta tank. It shouldn't be something in the water because I use the same tap water for all my tanks and both my 15 gal and Admiral are completely free of contamination. I've noticed that the film if I'm not paying attention will cover the entire tank and this morning it was actually trapping air bubbles below its surface I took pictures of all 3 tanks and then cleaned it up best I could. What do you guys think this is? And what should I do about it? I've included pictures of both tanks that are affected- the picture that looks mostly clear is after you start cleaning up the gunk it sticks together, it was easiest to show in the badly affected tank. Their tanks do sit at room temperature without heaters or filters and are each a little bigger than half a gallon. However, other than the fact that it's there it doesn't seem to be bothering the fish himself, he's just as active and isn't in stress colors.
Tetra 16837 BettaSafe Water Conditioner, 1
A filter is a must to help keep the water cleaner for longer. However betta fish do not like strong flowing water / currents. So what is recommended is a gentle aquarium filter, or one that has an adjustable flow. The filter will keep the water clean and healthy for the fish.
I filter my Bettas tap water then add the conditioner.