Weather loach & dwarf frogs together?

Question
We went to our favorite independently owned fish store tonight and purchased 2 dwarf frogs, a snail, and a weather loach to add to our small community tank.  It's a 10-gallon tank that already contains 4 hatchet fish, 1 plecco, 2 small catfish, 2 neon tetras, and 2 fan-tailed guppies.  This is the same store where we've purchased all of our fish in the past, and we've been very happy with the service in the past.

The problem we're having now is that when we got home and put our newest additions into a bucket to begin acclimating them to the tank water.  Everything was fine at first, but then the loach began pecking at (for lack of a better term) the frogs and the snail.  We tried to keep them apart but without any luck.  We reasoned that the reason for the "attack" was the small confines of the bucket, so we moved the loach into our tank.  He's been very agitated, swimming around very quickly all over the tank.  He's also pecked at several of the other fish if they get too close.

Did we make a mistake by getting a loach for this tank?  Is he going to try to eat our other tank inhabitants?  Any help or suggestions would be greatly appreciated!  Thanks!

Kelly

Answer
Hi,
I don't want to be sounding rude, but I have to put this plainly.
You should not be satisfied by the service of the fish shop, because they are misleading you.
This isn't your fault, I'm not saying it is, but there's a lot that needs to be put right if you want all your fish to live happily.
Firstly, your tank is overstocked.
No type of pleco would be happy in a tank that size, apart from bristlenose plecos, most will grow in excess of 10 inches. He really needs to be taken back to the shop. Do you know what sort of pleco he is?
Hatchet fish need bigger tanks really, and need to be in bigger groups, which you do not have space for.
Any type of loaches are very lively and need at least 30 gallons, and also need to be in groups, the larger the better. He will have been pecking the others because he was stressed. It's best you take him back.
Tetras need to be in bigger groups, so I would buy at least another 4 of them.
By "small catfish" I assume you mean corydoras? If so, buy another 1 or 2 of them.
You will then have 6 neon Tetras, 3-4 corydoras, and 2 guppies. That is your tank fully stocked then.
If you have any more questions, please ask.
Best wishes,
Kathryn