Clown Loach with an attitude!

I bought a Clown Loach about 6 months ago. During the time I have had
him, he's been fun to watch and appears to be very healthy. I thought
he could use a buddy so I bought a second one. The first few days they
resembled two old dogs circling and sniffing each other out. It was
really a funny sight. The couldn't get enough of each other.

The first clown I purchased is about 2 inches long and the new one is
around an inch long. Something happened while my back was turned one day
because now when the little one trys to get near the larger clown, the
larger clown body slams the little one away. The larger one has snapped
(lurched) at the smaller clown to keep him away.

They both appear to be very healthy, have good appetites and get along
with the other fish, just not each other. I have them in a 20 long with
about a 70% load on the tank overall. Water parameters are just fine, I
do weekly water changes and clean the tank the same time I do a water
change. All the other fish interact just fine. This behaivor is not
typical of clown loaches that I'm aware of. Any thoughts?

Mark