okay i have a 29 gal with 1) fig 8's 1 inches, 4) GSP's that are 2 1/2 inches , 2) GSP's that are 1 inches and now my girlfriend gave me 2) her " Takifugu ocellatus-Fugu puffer" that are 1 inches. and my questions are, one why do they dig themselves under gravel? and two Ive notice that in other...