Originally Posted by Oldfishlady
You also have to remember that this is a man-made fish with abnormal long heavy fins-its not fair to compare its needs to its wild cousins or short fin Bettas.....sometimes the smaller tanks are more suited for the long heavy fin male Bettas for that reason alone-to start out in and slowly move them to larger spaces and water movement to their tolerance......with some...not all.....they have never been in a container much larger than the temporary cups you see them in and they feel secure in this space and have not built muscle mass to swim properly-too large of a space too soon-this tires them-stresses them and in turn can compromise immune response-not to mention the delicate fins that soon look tattered due to swimming or fighting water movement....Don't miss understand...not saying they can only be kept in small unfiltered containers.....but that some-not all.....need to be moved to larger spaces and water movement in steps to their tolerance......
^this +1 ..
also to add to this .. from the moment you move them from their cup to something bigger .. if your monitoring your betta .. you can immediately tell what type of environment they will thrive in ..
bettas that want bigger areas will start swimming around and immediately start poking at their new boundaries .. trying to see how far they can go .. how fast they can swim .. and sometimes even bump into the tank walls cus it's too small for them .. it kinda looks like they are trying to "get out" of their space .. and want more .. this is clear behavior that should let you know they want a bigger space ..
i can't speak for bettas that likes lesser space .. (i know sick bettas and rescues need smaller spaces and lower water levels those are special cases cus they are sick) .. and since i haven't bought a betta that didn't appreciate the extra room .. i've never kept any of my bettas in less them 5g .. but i did have to condition them to be used to their extra space ..
they went from cup to .5 (2 weeks) .. then 1g (2 weeks).. then 2.5 (3 weeks) .. then to 5g .. and i know this helped out to develop their muscles over time so when i put them in their 5g environments they didn't spazz out and tear up their fins to swim faster (as what happened to my bf's betta when he moved him from cup .. to 2.5 -6 weeks- to a 10g ..) or become lethargic or scared for their extra room .. and they also no longer kept poking at the edge of their small environments "trying to get out"