Lack of information on the daily activity patterns of Litopenaeus vannamei (Boone 1931) might result in inadequate feed management strategies in shrimp farms. In order to provide information to improve feed management in shrimp farms, the daily activity of juvenile shrimp reared in glass aquaria was studied, using L. vannamei (7.57±1.01 g), equivalent to 33 shrimp m−2. Thirty‐two shrimp were observed, half in light and half in dark phase, over 280 h in 15 min h−1 windows. Feed was provided once a day, at 10% of tank biomass. Swimming, exploration of substrate, inactivity and cleaning were recorded through instantaneous focal sampling. During the dark phase, swimming was predominant and alternated with exploration. In the light phase, inactivity was predominant, and again alternated with exploration. Cleaning occurred evenly in both the light and the dark. Substrate exploration, which characterizes the search for food, occurred in both dark and light phases, with a most intense peak 7 h after light phase onset, indicating this as the optimal feed offer.

In shrimp farms, food partitioning during the course of the day is contradictory, ethology studies may help in determining the proper frequency. Litopenaeus vannamei juveniles were placed in 30 L aquariums (41m À 2 ), exposed to a 12:12 h light^dark cycle. Feeding was provided at 10% of biomass three, four and seven times per day, with observations made in 15 min h À 1 windows, initiated after the ration was o¡ered. Latency to access the feeding tray and to start eating was recorded using instantaneous focal sampling and digestive tract ¢lling (DTF) by the continuous focal method. Weight gain was recorded at the end of the experiment. We performed seven repetitions, with 28 individuals observed for 33 days for each treatment (490 h of observation). The threetimes o¡ering induced less latency for accessing the tray and for ingesting the feed as well as a higher DTF when compared with the other frequencies. Animals fed three and four times had similar weight gains, and were greater than those fed seven times. Our results indicate that a more spaced food o¡ering stimulates the search for and ingestion of feed. As compared with other frequencies, the three-timesper-day option assumes lower labour costs and a more e⁄cient use of the feed.