I'd listen to COWGIRL AND SAUCY!!!
turtles ARE ferocious to fish. love to nibble nibble nibble. lol.
it is very difficult and expensive to keep fish with turtles. dont recommend it for everyone. they will need to go into a seperate tank from the fish.
if u have more than one slider, than i would strongly suggest getting a 20g LONG tank. about 30 inches long, about 12inches wide and 12 inches tall. (somewhere around there.) turtles love to swim but as hatchlings are too weak to swim in strong currents so make sure that the filtration is not too strong, but still does the job. they're expensive but canister filters work the best! water quality is very important to the health of the turtles. poor water quality= poor health and disease. they require an extensive variety diet. look up REPTICZONE.COM they give u the basic information that u will need to properly take care of ur turtles. hope for the best
as for ur dragonfish. if he has small tiny eyes, ugly face a large mouth, slender body with colours ranging from light blue to purplish. spiny dorsel fin then it should be a dragonfish. its a type of golby from china. very aggressive "looking" but a very passive fish and should not be put with other aggressive fish, but however u should keep an eye out for small fish that can be eaten by him. they love frozen foods and are normally hard to keep because of feeding habits.
hope u have a HUGE aquarium for ur catfish. that guy can get 18-36inches in length. very big very active fish. and the myth about fish only grow to the size of their environments is NOT true. ur Catfish will need a bigger tank and a BIG tank fast cuz they have a very fast growth rate.
good luck.