Corys and Bettas

[alannalynn]

I just bought a new Betta for a 10 gallon tank that has 2 corys in it to bottom feed for guppies that have passed away. They are chasing the betta, swimming back and forth across the tank like they are marking their territory and won’t let him near the bottom of the tank, i’ve never seen them so active before. what is happening?

 

[SaraB]

I've never heard of corydoras being aggressive. What are your water parameters? Temp? Species of corydora?