Cool & great idea, Yea how i wish i can have 1 set-up like yours...

The freshwater shark looks real cool & rare (saw mouth) i've seen 1 before at Cichlids Forever (LFS) @ upp serangoon rd but the owner have to hide it after warning from AVA Wondering r u the buyer???

Nice rays u have there, base on your pond size, size don't really matters & who knows you might breed them succesfully
Places that sells wild caught rays or rare ones

1 Gan Aquarium
2 Cichlid Forever

What other interesting species you have in your pond

Cheers