According to Google/Uniblue , sgt file extension is also used by the Hitman game , if that means anything ? And I thought it stood for Sachs guitar track
. However , in investigating this , I found out that if you start the aquarium , bring up the settings box ( right click OR spacebar ) , click music playlist , add , and then click OK on the music playlist box , not the open media file box , then click on OK to return to the program , it stays paused because the open media file box disappears under the aquarium and stays open waiting for a response . In windowed mode , you'll see it and realise to close it , but in fullscreen , you probably won't . Just thought it worth a mention .
(P.S. Cliff - yes ! I too have a hankering for a great big turnip in the country )