I caught a 15cm T.L. elver in a river estuary in S.W. England. The sex an eel becomes is partly determined by environmental conditions such as crowding and food abundance. In areas where food abundance and water temperatures favour rapid growth rates, a higher percentage of male eels are found. The next problem was where to keep him. Temporarily, I have housed Neil in a 50 litre tank, but plan to move him to a larger tank in a few weeks.
Eels are non-discriminating and messy feeders.
Moved Neil to his final home, a 4 foot 120 litre tank. This has undergravel filtration and carefully cut cover glasses weighted with bricks to prevent escape. That they are fascinating fish, but tend to become nocturnal, so viewing opportunities are limited. Alternative shelter such as pipes, etc are accepted if the eel cannot burrow, but they never look very happy with this.