The long period of raising carp (Osphronemus gouramy) causes the need for excessive feed. One way that can accelerate the growth of this fish in order to shorten the maintenance period is by the addition of essential amino acids, such as lysine. However, this certainly gives its own influence on energy retention. Therefore, the aim of this study was to determine the influences of addition of lysine in feed on energy retention and feed conversion ratio of carp. The research method used an experimental method with a completely randomized design consisting of five treatments and four replications. The treatments used were the addition of Lysine 0%, 1%, 1.5%, 2%, and 2.5% to the feed. The present experiment was conducted for a year. The results showed that the addition of lysine as much as 2% in commercial feed can increase the energy retention of carp (Osphronemus gouramy). Moreover, the addition of lysine by giving up to 2.5% cannot reduce the feed conversion ratio in carp (Osphronemus gourami) rearing. It can be concluded that the use of lysine has different effects related to the increase in retention and decrease conversion ratio in carp.