The feed given to cobia’s juvennile (Rachycentron canadum) still uses expensive factory-made feed to be the basis of this research. This aims of this research to examine the effect of feed formula with different protein levels on optimal growth cobia. This research method  used a completely randomized design (CRD) with three treatments and three replications. The treatment in this study were different protein level commercial feed (as control/46%), and formula feed (protein P1 46% and P2 protein 48%). The parameters tested included absolute weight, daily growth rate, feed conversion ratio, protein retention, and survival rate. The data obtained were analyzed by analysis of variance and continued with the duncan test with a 95% confidence interval. The results showed that the growth of absolute weight and daily growth rates generated from each treatment were significantly different (p <0.05), K (80.30 ± 11.20c g and 1.78 ± 0.25c g/day), P1 (21.87 ± 1.95a g and 0.49 ± 0.05a g/day), P2 (37.43 ± 3.29b g and 0.83 ± 0.07b g/day).

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Wilayah pesisir merupakan wilayah datarannya berbatasan langsung dengan lautan yang mempunyai potensi sumber daya alam juga berpotensi untuk berbagai macam kegunaan. Adapun maksud dan tujuan dari penelitian ini adalah pemanfaatan dan penggunaan tata guna lahan yang sesuai RTRW Kabupaten Karimun. Tujuan penataan ruang wilayah Kabupaten Karimun adalah mewujudkan Kabupaten Karimun yang maju melalui perdagangan yang bebas dan pelabuhan bebas yang berbasis industri dan potensi local yang berwawasan lingkungan. Hasil penelitian ini adalah costal area merupakan hasil dari reklamasi pantai yang memanfaatkan kawasan yang tidak terpakai menjadi kawasan yang bermanfaat. Namun dalam pemanfaatan dan pembangunan kawasan pesisir harus dilihat dari segi dampak lingkungan atau amdal sehingga dampak negative dari pembangunan tidak memberikan dampak buruk bagi lingkungan.

This study aims to determine the optimal protein content in the feed for the growth rate of seabass (Lates calcarifer) through feeding with different protein levels maintained in the controlled tank. This study used a complete randomized design (RAL) with 46% protein content of commercial feed, 46% protein content of formulation and 48% protein content of formulation each treatment consisting of three replications. The results of this study as a whole of the parameters observed included absolute growth, daily growth rate, protein retention, and liveliness gave significantly different results between control treatment with P1 and P2, while for feed conversion ratio gave significantly different result between treatment control with P2, but not significantly different between controls with P1 and P1 with P2. .With the provision of seabass with different protein levels maintained in a controlled tank gives the best results in the control treatment with a 46% protein content.

In marine aquaculture, immersing marine fish species in fresh water can remove ectoparasite that adhere to all over the fish body. This study aimed to evaluate the impacts of combining microbial floc and microalgae Spirulina platensis in juvenile cobia diet on growth performance and stress responses after immersion in aerated fresh water for 15 minutes. The fishes were reared in concrete tanks for 40 days before collecting data on their growth performance. The stress response was determined by mea-suring both glucose and cortisol levels before (0 h) and after (1, 2, 4, 6, 24 hours) immersion. The fish-es fed on the 15% of combining microbial flock and microalgae Spirulina platensis diet showed the highest growth rate with the lowest feed conversion ratio compared to other treatments. The cortisol level of juvenile cobia in both the 15% and 30% combination of microbial floc and microalgae Spiru-lina platensis treatments did not increase during the first hour following the immersion compared to the control treatment. The glucose level also increased after one hour immersion in freshwater of all treatments. This indicated that feeding juvenile cobia on microbial flocs and microalgae diets had a retarding effect on the physiological responses (cortisol and glucose) after immersion in fresh water.Keywords: microbial, microalga, Spirulina, glucose, cortisol, stress, cobia