I want a floating plant for my betta tanks which are 2.5 gallons each. I was gonna do hornwort but that would grow thick and not leave my bettas with much surface space... So would duckweed be a good idea?
You most certainly can. Ive never had a betta but I buy duckweed from guys with betta tanks.
If the aquarium has lots of mystery snails or if the fish are herbivores, duckweed is fine. It grows very fast, and you can even make soup of it.
However, once that duck flies over an aquarium with no herbivores, the duck weed will be there forever. It becomes very invasive, and even if the stuff dries out, it will come back to life and completely cover the water surface. Hornwort is easier to control; in fact, bettas and other bubble nest builders often incorporate hornwort into their nests.
I have never tried Hornwort A.J I will have to give it a go
As for duckweed yes you can have it. I have it in my 5.5 gallon tank with my Betta.
I ordered it online and had it for a week before I even put it into the tank. I was afraid that it would take the whole surface and that it would leave my Betta with no breathing space, however, I had this stuff in my tank for 1 week and 1/2 and it is growing, but not excessively. It is fine. I have not removed any yet because only the sides of the aquarium have it. It does not over take as fast as others say. At least not in my tiny tank.
I have medium to high lighting and use liquid CO2 and fertilizers for the plants in my tank and it is doing well and not being excessively annoying. It gives the aquarium a natural look.
I do like duckweed. You can also try Guppy grass and just let if float. This plant was suggested by my Betta breeder here in CO. I also have asian-water moss, but this plant needs more nutrients to absorb or it will wither.
Hope this helps it is a beautiful plant others may think it is annoying, but I have found that it is a lovely plant.
I have duckweed in a ten gallon tank. I don't have a hole sheet just a few. They grow very fast and so I scoop them out and put them in a bucket outside. They are still growing outside. Duck weed should be fine just make sure you don't have a lot and remove some when they start to cover half your tank. You could have one hornwort if you like and will actually be more helpful for your betta than as an obstruction. I have a betta in my ten gallon tank and he is always swimming around and not lethargic.