Tetrodotoxin poisening in fish

[DancingFish]

Hello everyone. I'm a science student studying the transmission of parasites between fish species and have encountered a number of 'juvenile' parasites infecting the tissues of marine puffer fish. In order for these 'juvenile' parasites to be transmitted to the next fish species in their lifecycle, they would need to be eaten while still in the tissues of the puffer fish. So what I'm hoping that you guys might be able to help me with is information about how often puffer fish fall prey to predatory fish and if the ingestion results in tetrodotoxin poisening in the predator fish? If any one has come across anything that has been documented in books or journal articles or even just information from your own knowledge and experience I'd greatly appreciate your help

[Pufferpunk]

I have often seen posts (not usually here though) from folks stupidly adding a puffer into their large predator tank. The predator has eaten (or tried) the puffer & was found dead the next morning. I have read of this often often at http://www.monsterfishkeepers.com. Those guys are much more risky with their fish' lives than we are here.

[RTR]

Not everybody in the water is susceptible to puffer toxins. I can't cite a reference off the top of my head, but I believe that (some?) sharks are resistant. Certain other fish may carry a puffer toxin as well - which implies that they also must have some degree of resistance (some newts have very high resistance, more than puffers). Not all puffers carry the toxin - certain species are know to be only very rarely toxic. Plus they do not all carry the same toxin there are at least two in common puffer use.

Toxicity is known to be seasonal and strongly related to diet. The puffers themselves do not produce the toxin, it is bacterial in origin, and most associated with shellfish. Puffers, blue-ringed octopus, newts in The US and Japan, Frogs from Central America,etc. all get their toxin with their food. If that variety of creatures can withstand the toxins, the odds are that some of the creatures which prey on them can resist it as well, or at least potentially may develop resistance.

Parasites with complex life cycles are not at all guaranteed a full life cycle. It their intermediate host is not itself consumed by the final host, the parasite's life cycle is over at a dead end. Parasites have a high-risk lifestyle.

[Corvus]

Some sharks and also morays and puffers are not affected by ttx. Simply a matter of how the sodium channels of the nerves work. For articles try biosis and fishbase (food items or predatory fishes).

Myers, R.F. 1999 Micronesian reef fishes names toxic fishes eaten by Tiger sharks as far as I know, there's also a report on Gymnothorax ocellatus for eating toxic fishes (at least one puffer species, but family Diodontidae, which also posess ttx). Personally, I've seen G. favagineus eat puffers without being intoxicated. So two of the top reef predators seem to be resistant. You'll also easily find references on how and why puffers are not affected by ttx.

[DancingFish]

Thanks for the repliess guys.

RTR thats exactly what my project is investigating! Some studies have shown that parasites are capable of increasing their chances of transmission between diffferent hosts, making their lifecycles less risky than was originally thought (for example heterophyids parasitise the brain of the (second) intermediate fish host causing it to swim to the surface where it becomes easy prey for sea birds that act as the next (definitive) host in the lifecycle). My project is looking to see if the parasites are selective in which species of (second) intermediate host that they infect, part of which involves identifying potential dead end hosts and looking at patterns of infection. Thats why I am so interested in the parasites that are infecting tetraodontids - they are the only potentially toxic species that I have collected larval parasites from. I've found a lot of info about the causes, seasonality and variability in toxicity of puffers, which has added weighted to the plausible link arguement, and I also have two articles about tigersharks and dolphinfish preying upon tetraodontids (again adding weighte to the plausible link) but what i'm really interested in is if coral reef predatory fish such as serrandis, carangids and lutjanids are successfully preying upon tetraodontids or not.

[Pufferpunk]

Maybe this would be better placed in the Hospital Forum?

[Corvus]

What I can add, because I happend to stumble over it this morning is another puffer (C. rostrata) predator: Sphyraena barracuda.
This is confirmed by fishbase
http://www.fishbase.org/TrophicEco/Pred ... e=rostrata

For the other groups you are interested in try searching puffers on fishbase (use the predator tab to find their confirmed predators) or browse the predators and use their "food items" tab. You'll also get literature references from short texts on the species' pages.

[Corvus]

PS:

A serranid as predator of C. margaritata:
http://www.fishbase.de/TrophicEco/Preda ... argaritata

and the proper reference:
Randall, J.E. and V.E. Brock 1960 Observations on the ecology of Epinephelinae and lutjanid fishes of the Society Islands, with emphasis on food habits. Trans. Am. Fish. Soc. 89(1):9-16.

I would work this way for some of the information you need.