Background:

Cherax quadricarinatus (von Martens, 1868) is an australian freshwater crayfish (Decapoda, Parastacidae) of great commercial importance in tropical and subtropical countries. One of the most timportant aspects to increase its commercial production is to optimize growth and survival rates, wich change with developmental phase and habitat quality.

Goals:

Determine shelters presence effect, on growth and survival rates of early juveniles through of different shelter number per crayfish.

Methods:

Three densities were assayed: without shelters (T1), one shelter per individual (T2), and two shelters per individual (T3). Thirty juvenile cray fish on III development state (external feeding onset) (114.33 ± 3.5 mg) were kept in 1000 L tanks, with two replicates per treatment, at 24 °C, for 92 days. Crayfish were fed every day with commercial balanced feed (48% protein).

Results:

Growth rates were higher in treatments T2 and T3 (0.065 and 0.055 g d-1), both significantly different fromT1 (0.030 gd-1). In contrast, no significant difference was found among treatments in relative growth weight to length,which showed a positive allometry (b = 3.09-3.26) and final survival either (80-85%).

Conclusions:

Presence and number of shelters increase growth of freshwater crayfish, notably .One shelter per individual is enough to obtain early juveniles Cherax quadricarinatus with high weights and lengths.