Environmental substrate selection and daily habitual activity in Xiphopenaeus kroyeri shrimp (Heller, 1862) (Crustacea: Penaeioidea)

shrimp. Six different substrate combinations were tested using silt and clay, various granulometries of sand, and gravel. Experimental tank for preference testing consisted of a 50 cm diameter cylindrical tank with 6 lateral compartments and a radial area in the middle. Every substrate combination prepared was randomly chosen for each compartment. Each substrate was spread to have a 5 cm thickness in the compartments. One isolated individual for each trial (n= 40) was used. Activities of the animals were observed 8 times a day, at 13:30, 14:30, 17:30, 18:30, 0:30, 1:30, 7:30 and 8:30 h.