Thanks for the quick reply! I have had this tank for about 5 years, starting with one betta in a little bowl and winding up with this tank, which is 20 gallons and has both undergravel filtration and a carbon filter system. It has several kinds of plants and rock formations so that there are plenty of hiding places at all levels, and the lily pads on the surface ( half the plants are real and half are fake). The tank now has the betta pair (this is the 2nd betta male and first female), an albino cory catfish, one small algae eater and a a trio of platys (one of them randomly gives birth to 2 or 3 babies every few months and usually they all live, so I have had the family line of platys living in the tank the entire time - if the number reaches more than 5 platys I will give away the fry, but usually the number stays at 5 since the platy seem to only live about a year). There are several trapdoor snails also, so the tank is very clean and has lots of oxygen in the water. I had the male and female betta in different tanks, and put her in when the male began to make bubble nests and the signs said he was looking for love. I put her in and nothing happened, but they seemed much calmer together so I left her in there. They swim around together in the tank and never show aggression toward each other or the other fish. I know they shouldn't be together, but they don't fight and don't seem to be interested in breeding, and they really seem happier together.The female has been in the tank for the last 4 months ( the male was there for almost a year), and this sunbathing on the lily pad behavior has just started. There are lots of plants for hiding at the bottom and middle of the tank under the lily pads, and the lily pads themselves are usually home to the baby snails until they get big enough to no longer be food for the fish. It just seems so odd for her to start this behavior after being in the tank for months, and I thought maybe it was a normal behavior that I just had never seen before. She does not seem to be trying to get out, since I left her on the lily pad this morning and she went back into the tank on her own.