Hi its been a month still My 2 iridescent shark 1 albino just 5 inch and 1 black is probably 6 inch they always hiding or to be exact they just stay at the bottom corner of my pond whole day time dont even eat but in night some times they come specially when i feed its an outside pond 7ft x 3ft x 3ft so size and it has 6 koi fish 5 to 7 inch and 1 pleco and 2 small black gold fish( i will switch them in my next aquarium project) and 1 small pleco...in shop they were in 3 ft tank 30 or so.. but active and wandering...please give me a solution or i have to tive them back cz it's depressing.. and i put brick cz they used to hide in the fold of pond liner and i always get heart attack