Electropositive shark repellent Atlantic longlining vessels in 2008. As expected, teleosts (bony fish) are not repelled by the electropositive metal’s cation liberation in seawater. This is because teleosts lack the ampullae of Lorenzini. Teleost response was confirmed using captive Cobia ("Rachycentron canadum") and Pacific halibut ("Hippoglossus stenolepis"). In July 2008 swordfish ("Xiphias gladius") catch was reported on experimental hooks treated with electropositive metal. As with all shark repellents, 100% effectiveness will not be achieved with electropositive metals. The metals are particularly effective when the shark is relying on its electrosense. It is likely that electropositive metals are ineffective for deliberately stimulated (chummed) sharks,
Demersal fish is pointed downwards; this is beneficial as their food is often below them in the substrate. Those bottom feeders with upward-pointing mouths, such as stargazers, tend to seize swimming prey. Benthic fish, sometimes called groundfish, are denser than water, so they can rest on the sea floor. They either lie-and-wait as ambush predators, maybe covering themselves with sand or otherwise camouflaging themselves, or move actively over the bottom in search for food. Benthic fish which can bury themselves include dragonets, flatfish and stingrays. Flatfish are an order of ray-finned benthic fishes which lie flat on the ocean floor. Examples are