I did catch 5 crabs, 4 larges (around 1.3~1.5 cms wide) and a small one (less .5 cm).
By the time I went back home, I found one of the bigger snacking the small one Cannibal!!!
Though, I decided to put them in the tank, I'm so upset with these @"! ramshorns ...
After drip acclimatation, I drop them in the tank, and they immediately disappearred under the driftwood.
That was a week ago, and I haven't seen them till this day. Though, everything seems normal, the 4 discus are fine, so are the other fishes and the red cherries.
The positive point is that it seems the ramshorn are decreasing in number.
I cross fingers.