Those feeder blocks are not even suitable for large fish and as they have plaster of Paris added, the water chemistry may be altered in the process unless you hope the hardness levels to increase. Forget the blocks and just fast them for two weeks.
people starve them for a few months sometimes trying to break them off of live. So 10 days is nothing to worry about as long as they are not really small juvies.
I would just do a large wc and then feed heavy the day you leave.
but i have two silver dollars,tinfoil barb,fire eel in the tank so i have to feed them somehow the fire eel should be fine if the barracuda and gar will be fine
IMO any healthy non juvi fish can go 2 weeks with out food with no real danger of starvation.
The only worry would be if any of the fish are small enough to be eaten by there tank mates.
If the cuda and gar and eel are on live foods, just put enough feeders in the tank to last them a few days. That way they will be full and not be eyeing any tank mates.