AACL Bioflux, 2016, Volume 9, Issue 2. http://www.bioflux.com.ro/aacl 422 Squid ( Loligo edulis) ink raw extract as an anti– vibriosis substance in grouper ( Epinephelus fuscoguttatus ) juvenile culture infected by Vibrio alginolyticus 1 Mohamad Fadjar, 1 Sri Andajani, 2 Kartini Zaelani 1 Department of Aquaculture, Faculty of Fisheries and Marine Science, University of Brawijaya, Malang 65145, Indonesia; 2 Department of Food Processing Technology, Faculty of Fisheries and Marine Science, University of Brawijaya, Malang 65145, Indonesia. Corresponding author: M. Fadjar, f4dj4r_02@ub.ac.id Abstract . In mariculture Vibrio alginolyticus is frequently isolated from vibriosis sick grouper, Epinephelus fuscoguttatus. The high mortality of grouper larvae in grouper hatchery as vibriosis cases need a way to overcome with other antibacterial products. Squid ink, as a squid waste product, which contains a variety of bioactive components which are environmentally friendly was used as an anti vibriosis substance. The methods used in this research were: Phase I: extraction of squid ink; Phase 2: Paper Disk Test, Scanning Electronic Microscope (SEM) observation, and GC-MS chromatography test for the active ingredient; Phase 3: in-vivo trials on squid ink extract against V. alginolyticus in tiger grouper juvenile. An experimental method with completely randomized design using three treatment doses of squid ink extract (365.5; 312.5; 265.5 mg L -1 ), after preliminary test using Minimum Inhibitory Concentration (MIC), to treat the infected juvenile with V. alginolyticus each with three replications was used. Blood samples were investigated for hematological profile i.e.: erythrocyte, leukocyte, monocyte, lymphocyte, and neutrophile. The conclusion of the research results were squid ink extract can be used as bactericidal for V. algynolyticus at a dose of 265.5 mg L -1 . Squid ink contains 9-octadecenoic acids/oleic acids as an antibacterial agent. The tiger grouper juvenile which was infected with V. alginolyticus reached 100% survival rate after squid ink extraction treatment and gives a highly significant effect to hematological profile. Key Words: squid ink, V. alginolyticus, E. fuscoguttatus, survival rate, hematological profile. Introduction . Grouper ( Epinephelus fuscoguttatus) is one fish species that has a very high economic value in Indonesia. Therefore, it is widely cultivated and especially important for export to the country of Singapore, Taiwan, and Hong Kong. Therefore, this species has great potential and is promising as an aquaculture product. The limited seed supply, both in terms of quantity and quality is still a major problem (Sugama et al 2012). One of the obstacles encountered in grouper aquaculture is primarily pathogenic bacteria attack on the larval stadia and seeds. The occurrence of these pathogens ommited causes loss of quality and production efforts on grouper hatchery, harvest failure and even death (Hatmanti et al 2009). Vibrio illness is called vibriosis, penaeid bacterial septicemia, penaeid vibriosis, luminescent vibriosis or red leg disease (Aguirre-Guzman et al 2004). This disease is a major bacterial disease, especially at the seed can lead to mortality up to 100% within 2 weeks. Several species of Vibrio bacteria are frequently isolated from diseased groupers (i.e. E. coioides (Huang 2005), Polkadot grouper, Cromileptes altivelis (Nitimulyo et al 2005) and tiger grouper, E. fuscoguttatus (Desrina et al 2006)): Vibrio alginolyticus, V. anguillarum, V. vulnificus (Nagasawa & Cruz-Lacierda 2004; Nitimulyo et al 2005). Signs of the disease include fatigue, tissue death, slow growth and metamorphosis, disability, bolitas negricans, bioluminescence, muscle opacity and melanization. In many cases, opportunistic Vibrio, which only cause disease when the host organism immunity