Be really care when knocking these things out from a distance! Unfortunately they don't look knocked out when they are so continuing to shoot darts at them can be an easy an unfortunate mistake to make.
Real Dino tamer tame Anglefish with wooden club in deep sea
Angle fish have very low hp and big torpor, made it painful hard to tame high level one. But it's not impossible, you can easily tame a lvl 150 one with a tanky Bary.
Prepare: some scuba suits, 1 full scuba set, 1 tanky Bary set to passive, 1 wooden club and crossbow, arrow, some tranq arrows since you not gonna need a lot of them. Some regular kibble to tame it, and toxin if you want (since you can farm on site with crossbow on Bery back)
Tame: Clean up the site with crossbow and Bary, grab Toxin that floating around after shoot them. Get close to the target fish and shot it with tranq arrow till it start to flee, flee away if your Bary getting low to eat nearby sharks for recover it hp.
When it start to flee, phase 2 start, stop shooting tranq arrow or you will kill the angle, time for get close and personal with a club, your Bary will not likely to run out of stamina underwater if you don't tail spin anything, so just speed it up and club the fish down.
After it got knocked up, give it regular kibbles and off to do your own things, you have loads of scuba suits after all, kill some alpha fishes, kill some whales, kill some turtles, but remember to keep an eye on the fish torpor as it drop pretty fast while hunger drop very slow. Feed it toxin till it tamed(toxin is better because you can farm them easily with crossbow while waiting for it getting tamed)