Why does Betta jump out of tank

Jan 23, 2018
HI! So I have had betta fish for years and community fish for years as well. Grew up with always having tanks of different sizes. My question is about my betta fish experience. I usually have a betta in a 2.5 gallon tank that I keep clean. What I noticed is that my bettas can thrive for a long time and then all of the sudden jump out when no one is home. My tank does have a cover. So the betta finds the tiniest opening and manages to jump out. I never figured out why. Recently I had a betta that I had for a long time and he was in that tank and after being in there with a new tank mate for about 2 months, he jumped out when no one was home. So any input on what may be a cause for bettas to jump out by finding a little tining opening, let me know. Thanks!
PS, my tank has a heater, has a filter, gets water changes, looks clean, just so you have that info.