What size tank are you using?

 

Bettas are tropical fish & the water temp should be 76F-80F. If you are in a tropical climate or your room temp stays in the high 70's then you wouldn't need a heater. I would suggest getting an in tank thermometer to see what the water temp is & if it stays a consistent temp.

 

My tank is a little more than a litre

 

Try to get at least a 3 gallon tank. With how small your tank is you will have to be changing water daily just to keep it clean. Like Shellica said get a thermometer and check the water. Keep it around the 76 to 80 Celsius. You will have a happier fish and get more enjoyment of it with a bigger tank.

 

A 2 gallon would be ok too. I have both mine in seperate 2 gallon tanks and it seems to be a nice size for them. And my tanks only cost $30-35 each.

 

I got a 1.5 gallon tank, which I know is smaller than recommended, but I plan to change the water frequently and I have a mini filter and heater. My house gets really cold (low 60s sometimes) so I got a preset heater for 78 degrees F, and a tank thermometer. The setup seems to be working out perfectly right now.

 

Welcome to the forum megmuise, ambientnight and writergirl

 

Many bettas are kept in tiny little display tanks, known as a Betta-hex, and do quite well.... They are extremely hardy lil fish! At one time, I had upwards of 30 boys in these little hex tanks, and about 6-8 females in an unfiltered, room temp planted 10 gallon, tho I never had any luck breeding them! Granted, I spent a lot of time doing water changes & re-arranging neighbors, but the fish didn't seem 2 mind their small spaces.... Most of them lived for over 3yrs!
My current crowntail, Poisson, lived in a 1 gallon tank, with no filter or heater for nearly 3 yrs.... and aside from developing recurrent dropsy, did just fine. He even survived 2 big moves (in a milk jug, lol), from TX to FL, then to AL. It just really depends on water change frequency & placing unheated tank in a warm, draft free area. He just recently inherited a 3.5 gallon tank, which is filtered & heated, thx 2 a heater malfunction that killed all the fish residing in it (don't worry, I have replaced the bad heater ) Good luck in ur new Betta adventure... They r easy 2 keep &fun 2 watch!

 

A 1 gallon is fine provided that it is heated AND you are willing do the right amount of water changes a week - which is a 100% water change and a 50% water change. However if you ever get the chance to upgrade to a larger tank, Im sure he will tank you for it :-D

 

I would definitely advise you to get a bigger tank. 1L is is roughly a 1/4 of a gallon, and you are going to be fighting an uphill battle against rapidly deteriorating water quality with such a small volume of water. I don't think they even make heaters to fit tanks that size, at least not good heaters anyway.

I am not someone who likes to see bettas living in unheated tanks unless your house is kept heated to an appropriate temperature or you live somewhere with a hot climate. While many bettas can tolerate lower water temperatures, this doesn't negate the fact that they originally evolved to inhabit tropical regions such as Thailand/Malaysia/Indonesia etc.