Males and females flare or puff out their (opercula) to appear more impressive, either to intimidate other rivals or as an act of . Other reasons for flaring can include when they are intimidated by movement or change of scene in their environments. Both sexes display horizontal bars if stressed or frightened. However, such colour changes, common in females of any age, are rare in mature males due to their intensity of colour. Females often flare at other females, especially when setting up a . fish behave similarly, with vertical instead of horizontal stripes indicating a willingness and readiness to breed (females only). enjoy a decorated tank, being a territorial fish it is necessary to establish territory even when housed alone. They may set up a territory centered on a plant or rocky alcove, sometimes becoming highly possessive of it and aggressive toward trespassing rivals. This is the reason why when kept with other fish the minimum tank size should be 45 litres (about 10 gallons). Contrary to popular belief, Bettas are compatible with many other species of aquarium fish. Given the proper parameters bettas will be known to only be aggressive towards smaller and slower fish than themselves such as .
7 Fundamentals of the Ideal Betta Fish Tank - TFCG - Jack Dempsey
Skye: I'm sorry about the loss of your Bettas. I read your other comments about the glass surfing and lethargy. It really sounds like you had some kind of water quality problem and/or tank size issue. If you are unsure about the safety of your water see if a local fish store can test it for you before you buy any more fish. Also make sure each Betta has a bare minimum of one gallon of space in their individual tank, though I'd really prefer to see them in 5+ gallons each.
The Ultimate One Page Guide to Betta Fish Care
Hi Juliana. Like most fish, Betta need a day/night cycle, so light on in the day and off at night is fine. If he is flaring too much when the light is on in his tank, but off in the room, trying keeping the light on in the room whenever it is on in his tank. A little flaring is not a problem, but too much stress is no good for him. Good luck!
Choosing and Setting up a Betta Fish Tank - A Beginners Guide