It may have "looked" like he kept that catfish, but we can't tell from the video. Personally, I'm thinking he just set it on the floor of the boat while he was getting the carp out of the net for the CPR. Who knows?
If you watch some of their other videos, it's pretty obvious these guys are novice anglers. Casting technique and reeling fish all the way to the rod tip are sure cues. So it is possible that they are ignorant of the law related to cast nets and game fish, but just can't tell from the video,.
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"Things turn out best for those who make the best of the way things turn out" - Zachary Troy Schrah - a young man with vision far beyond his years.