Most likely it is euprymna scolopies, which is a species from hawaii. They only reach ablout 1.5 inches and are tan but can show some red/brown colouration. They only live about 6 months so if they are already adults it will probably only live a month or two. As far as care they do not need a big tank a 30g would be big enough for one or two. However they need a fine sand bottom about 1inch deep to hide in. They are nocturnal so they usually only come out at night. As far as food we feed ours small live shrimp.