Please, please,please NEVER keep a male betta with another betta! they will fight(they are called siamese fighting fish for a reason!!!) you can keep females together(in at LEAST a 20g) but your still at risk to a bloody tank one day. Also betta NEED 5g MINIMUM! there sending there whole life in their afterall. How would you feel if you were living in a box, you would want it to be pretty big right! They need a filter(sponge is best for them) to clean the water beter and to help cycle it. a
heater too. they are tropical fish after all. plants are also a must(real or fake, but fake can only be made of rubber or silke otherwise it will rip their fins)(real plants will clean water too, and not all need a fertiliser) they get O2 from the water so make sure there is a
airstone or the filter pushes air down like mine dose. Betta also like to sit at the bottom of the tank because there fins are heavy, so a nice soft substrate will help!(also with real plants, mine LOVES his
anubias nana) you can give them tank mates, but be careful he can and will chase them, so get fast ones like
neon tetras(there schooling fish so get 5 at least) but be careful neons and other schooling fish are often known to nip fins. bettas despite there colorful appearance can be quite shy. so give them a place to hide when he wants to.
parameters. the temp needs to be 75-84. No amonia, no
nitrites, low
nitrates(not at 0 because you may not know if something is wrong with the cycle) bettas prefer more acidic water 6.8-7.2 preferably. they also prefer softer water(less minerals in it) Also don't get too strong a light, it is also part of the betta can be shy thing.
I know it seems like a lot to manage but its really not you can get a
API master test kit to test
ph and the 3 chemicals of the
nitrogen cycle! You are clearly new, so i tried to explain why each thing is and why its important. If you get it all under control, you will see a vivid colors, and there fins may even grow a bit, they will be happy, not just alive, and you will get to see them trive!