These fish are highly aggressive, invasive and eat other native fish eggs. Encouraged to kill after catching. I dropped my line in a spot and got a bite within 10 seconds. Simple drop shot right, size 8 hook. Chunk of Bar-S Classic Franks as bait, carefully covered hook tip to ensure it didn’t get caught on reeds. Happy to answer any questions.
Looking at the second pic, a Bar S hot dog is ~20mm in diameter, and that fish appears to be about 5 hot dog sections long, so I’d say it’s like 90-110mm long so roughly 4 inches in Imperial.