If you get into Japanese figures, then it's fairly easy to get some of these.
-There is no cone snail figurine to date AFAIK. I did a homemade Marbled cone at 1:20 scale.
-Glaucus atlanticus have an unbeatable representation by Ikimon-Kitan Club Nature Techni Colour. Belongs to the series "Seaside Creatures" and it's a magnet. Released in 2018, is still in production and many collectors have it. I think is near scale 1:1.
-Box jellyfish. The only one I'm aware of, belongs to the venomous creatures set by Kaiyodo CapsuleQ "The Complete Poisonous and Dangerous Creatures", that also includes two colour versions of Salamandra salamandra, one (about 1:2 I think) Scolopendra hardwickei, one (about 1:15 I think) Potamotrygon leopoldi (in my wishlist), and the (1:1?) box jellyfish that belongs to species Carybdea brevipedalia. Released in 2021, they're in production. But probably will be difficult and expensive to get the cubozoan alone instead the whole set.
-Barracuda. You saw in recent posts of this thread that I got the superb Kaiyodo Aquatales great barracuda. It's in production and still relatively cheap. There are other barracudas in the trade, the second better would be probably the Chap Mei barracuda that is much larger than the Kaiyodo counterpart and a bit too comical/exaggerated but still realistic. Other barracuda figurines such as K & M or Club Earth are discontinued, hard to find and worst in quaility/appareance (the Club Earth almost looks like a trout).
-Stonefishes. Only one I'm aware of: the Safari LTD Synanceia verrucosa. Very well done, about scale 1:10-1:12 I think, it belongs to the Venomous Creatures TOOB (together with bat ray, tarantula, cane toad, Indian cobra, fat-tailed scorpion, giant centipede, Komodo dragon and yellow-bellied sea snake) and I think it would be more difficult to get and more expensive alone instead buying the whole toob. Apparently, it's still in production so it would be not difficult to find. By casuality I've found one that I was not aware of: the Colorata Coral Reef Fish box one (read next paragraph).
-Lionfishes. Multiple options available. First, the genus Dendrochirus have a very good 1:10-1:12(?) representation in the Colorata Coral Reef Fish box, that also includes clown anemonefish, clown triggerfish, emperor angelfish, humphead wrasse, moorish idol, ribbon eel, saddle butterflyfish, spotted garden eel, Stonefish, Yellow Boxfish and Yellownose Prawn Goby. As always, is better to buy the whole set than the zebra lionfish alone. However, maybe for you is better to buy only the lionfish since the other fishes are not poisonous. The set is still in production and available. Besides that, a much lesser known, and I assume retired, Zebra lionfish is produced by Action Products, series "Deadly Kiss", and a Twinspot Scorpionfish of not the finest quality was produced by K & M and has been retired since long ago. Switching to the genus Pterois there are multiple options too. The best one is undoubtely the Yujin Luna lionfish that scales perfectly well with the Colorata Zebra lionfish, the quality is unbeatable. It belongs to the series Primary Color Saltwater Fish Book 1 together with 17 more species of tropical reef fishes, mostly not poisonous (except a porcupinefish and a yellow tang). Sadly it's discontinued but I saw recently various collectors buying the whole set so it don't must be still too difficult to get. Another Luna Lionfish was produced by Kaiyodo in the series Enoshima Aquarium Animal Pictorial Book 1. Released in 2004, this set is discontinued and I know that at least some of the figures are hard to find and expensive now. Other poisonous creatures found in same series are Lagoon jellyfish and Long-spined porcupinefish, together with many other sea creatures (a sea turtle baby, a penguin, a lobster and 12 species of bony/cartilaginous fishes). K & M also did a Spotfin lionfish, of not very long quality and long time discontinued, but if you can get the whole set it belongs to a Venomous Creature Tube that also includes a bird-eating spider, blue-ringed octopus, blue-spotted stingray, rhinoceros viper, coral snake, crown-of-thorns starfish, emperor scorpion, giant Peruvian centipede, Pacific sea nettle, blue poison dart frog and yellow-bellied sea snake. But too hard to find I suppose.
-Surgeonfishes. Being colorful reef fishes very often seen in aquaria, logically they also had wide representation in figurine form. Acanthurus leucosternon was produced by K & M and by Club Earth (both discontinued), Paracanthurus hepatus is by far the most widely represented species with no less than 9 brands releasing it (AAA, Animal Planet, Club Earth, Learning Resources, Mojo Fun, Papo, Safari LTD (4 different versions!), Schleich and Yujin, being the Learning Resources, Mojo, Papo, Safari and Schleich strill in production and the Papo and the Safari Incredible Creatures the most superior in quality (the only ones with scales sculpted) while the Schleich only can be bought together with an anemonefish, rabbitfish, seaweeds and floor base. Finally there is the Zebrasoma flavescens, another species with multiple choices including Yowies USA (in production, and good quality), Yujin (discontinued, see paragraph about it in Lionfish), and Kaiyodo (discontinued and little known, but nicely setting in an Acropora coral that is itself also a poisonous animal).
-Rabbitfishes. Besides the aforementioned Schleich common foxface that you must buy with anemonefish and Palette surgeinfish, two seaweed and a seafloor, there is also a Learning Resources one (not the finest paintjob, since the white areas of the head are painted blue), that is still in production, and a completely unknown for me (I assume long time retired and hard to get) Wing Mau White-spotted Spinefoot that belongs to a set "Saltwater Fishes" with other 4 fish species that I never heard about in any collector circle and I don't find even any picture of.
-Pufferfishes. Too many to choose including both Porcupinefishes (Diodontidae) and Pufferfishes (Tetraodontidae). For the former, Bullyland did one (discontinued in 2007), Safari LTD did one in the Incredible Creatures line (discontinued in 2018, but I think still possible to get) and one for their Good Luck Minis (in production), Yujin did one in the Primary color saltwater fish volume 1 (aforementioned in the lionfish section) and discontinued, and Yowies AUS did one with the characteristic ugly style of this brand, and I assume discontinued. About pufferfishes, the only one that I find that is not discontinued is the Colorata "Saltwater Fish Box" tiger puffer that I have out of my collection due to excessive size for my taste. Buying the whole set is the only option for get it enough cheap. Other pufferfishes such as Kaiyodo Valentin's sharpnose (Japan Aquarium Vol. 5), Kaiyodo Grass Puffer (Furuta Chocoegg Japanese Animal Series 4), Yujin Grass Puffer (Primary color Freshwater Fish book 2), Yowies AUS Black-spotted puffer (Series 4), and Play Visions pufferfish (Tropical Fish) are discontinued.
-Stingrays. Just too many tons of figures to choose for list them here. I just will mention the brands: AAA, Bullyland, Chap Mei, Club Earth, Colorata, Diramix, Fauna Figures Fishes, Innovative Kids, K & M, Kaiyodo, New-Ray, Playmobil, Safari LTD, Sun Wai, Trendmasters, Wenno, Wild Republic, Yowies AUS, Yowies USA.
-Weevers. These fishes are mostly ignored by animal figurine makers. Only the Spanish-Italian brand "Planeta DeAgostini" did a couple of weevers, a Spotted Weever and a Greater Weever, the latter of which glows in the dark. This brand had its glory in the 90's and sold the figures as accesories with printed matter or in blind bags, and I assume those weevers would be practically impossible to find for sale.
-Chimaeras. I have in my collection the Kaiyodo Deep Sea Odyssey 2 Silver ratfish, that is wonderfully well done. Sadly it's discontinued. Colorata did the same species, in the Deep Sea Fish set. Also very good one. Maybe still in production. Discovery Science did an unidentified chimaera of extremely simplistic style, released in 2018 but already discontinued.
-Dogfishes. Discovery Science did a Birdbeak dogfish in the set "Isle of Jaws". Probably hard to get, and like the others of this brand the quality is not the best but the species is exciting. Colorata did a cookiecutter shark that I have, belongs to the Sharks of the World Deluxe Box and is still in production. Catsharks are alternatively named dogfishes, I'm not sure if you're referring to these instead.
-Striped eel catfish. Only one figure I'm aware of, Yujin Primary color saltwater fish book 2 figure consisting of 6 catfishes swimming in dense congretation (as typical for this species) on a seafloor base. It's discontinued.
-Cuttlefishes. Many to choose. AAA did a very large one not very well painted, belonging to series "AAA Molluscs", I suppose it's discontinued and it's completely unknown in collector circles. Bullyland did a Sepia officinalis in "Exotic Sea World" series, not a superb figure but still nive, tough discontinued in 2007 so will be very hard to find. Kaiyodo did a very good Sepia latimanus in the series "Squid Strap Collection" and it's still in production. The same "Squid Strap Collection" also have a Metasepia tullbergi very well done and an unbeatable fabulous Sepia tokioensis of top quality. Also Kaiyodo did a different, more simplistic version Sepia latimanus in the "Furuta Chocoegg Japanese Animal Series 2", discontinued. Panini did a simplistic one in blue colour belonging to set "Marine Animals". Takara Tomy did an unbeatable Sepia latimanus in the "3D Capsule Encyclopedia Cephalopods" series. Woooooah look at those eyes!! Incredibly well done! And it's still in production! Same series also contain a very good Metasepia tullbergi. Yowies AUS did a Sepia apama with the characteristic weird style of this brand and very striking colours. Yowies USA did an infinitely better Sepia apama in Series 5, that is still in production and it's in my wishlist.
I hope all this will be useful to you.