This is my sisters Syno, she has had it years and has no idea what it is, she hasnt got any other fish with it but it's certainly too big for it's tank and she's giving me the tank anyway, so I don't want the Syno and we need to pass it on
Looks like a very skinny eupterus to me, though it's hard to tell for sure from that pic. Check out planetcatfish.com to compare it to pics of eupterus and other species of Synodontis.