The year 2 and 3 children inspected the eel after it was fished from Quarry Creek by Fish and Game Otago ranger Steve Dixon.
He showed the pupils how electric fishing was used to discover what lives in the creek.
Quarry Creek runs through the school's grounds but its water quality in that stretch means there is no life, so Mr Dixon took the group further down the creek to where it met the Owhiro Stream.
It was there he found the eel and was able to show it to the pupils.
''It's good for the kids to see what is in their backyard and get out of the classroom and looking into a stream to see what is there.''
Using the electric fishing equipment, a current is put into the stream, stunning any fish life, enabling him to pick up fish in the net and put them in a bucket.
In streams which are monitored, the fish are measured and identified before being released back into the waterway.
There is little fish life in the stream but finding the eel means the creek is healthy enough to support life in some patches.
Former teacher Christina King said the school had monitored water quality in the creek, which runs into the Owhiro Stream, since 2006.
Seeing a real fully grown eel had delighted the pupils and they spent the next few days investigating what type of eel it was and where eels came from.
''They're really interested after seeing it. We were very lucky.
''We were hoping to catch a native fish but we didn't see it,'' Ms King said.
The school hoped to put together all its monitoring data on the creek and present it to the Otago Regional Council with the aim of getting something done to improve the water quality, she said.
