Reptile & Amphibian Forums

are fish good for basilisks? Ours seem to love them, I just want to make sure it isn't unhealthy. We give him approx. 6 live ones a month in his water bowl. He spends an hour stalking them, then "fishing". He really seems to enjoy it.

live fish are very nutritious, as long as they are free of parasites. Never feed unhealthy or thin looking fish, or any with visible cysts and you will be okay.

We use minnows from a bait store. Are these safe, or should we be using feeders from the pet store?

Both sources are about the same. The important thing is to inspect there holding tank and see if its dirty or has alot of dead fish. I 'd go with the cleanest place. Check your minnow carefully, I don't use minnows because around here there are alot of encysted parasites on them. If you see what appeared to be a yellow or white dot immbedded in their muscle tissue ditch'em. You can freeze them prior to feeding if your worried about it. That will kill the parasites.

It's funny you mentioned freezing them. He never eats them all so we throw the remainders in a baggie in the freezer. We thaw them and he doesn't seem to mind they aren't alive.

Unfortunately, freezing will really only kill adult parasites, it often doesn't harm eggs or cysts. However, most parasites are very host specific, and it is unlikely the parasite in question would infect your lizard unless A) it normally includes reptiles in its lifecycle and B) the fish (and its parasites) come from the same general area as your dragon.

Hookworms, roundworms and strongyloides That infect fish can infect reptiles, most of are intended for birds, but with make due with your waterdragon. There are Flagellates and Cestodes that also can transfer from fish to herps. As you have said freezing doesn't kill all eggs or cysts, but doing so will reduce the parasite load and assist your waterdragon in controlling them. All lizards have some parasites, they have a short digestive tract and a strong immune system for dealing with them. Generally, when they become a problem, its the cause of additional stress that the animal is enduring.

According to a parasitology professor at my university, even most of your hookworms and such are quite host specific. There are indeed some fish parasites that can be transfered to more general hosts, including reptiles, but the chances of such an event are about on par with you getting nailed by an out-of-control car as you leave your house. The far greater danger in feeding "feeder" fish to your herps is the high contamination most of them have been exposed to with the various medications they get subjected to for treating parasites and diseases. There's a reason why the labels on fish medications say "for ornamental fish only". These contaminants get stored in the fatty tissues of the fish, through a process known as bioaccumulation, and the feeding of these to higher trophic levels (ie. your herps) causes biomagnification of the contaminants.

What are the symptoms? There are many herps that often fed a strict diet of goldfish. I've never heard of this occuring, but I imagine if it did, it would be hard to diagnose.

That will depend entirely upon what contaminate they have ingested. Admittedly, I'm not saying that feeding your reptiles "feeder" fish WILL lead to problems, just that the chances of it are higher. Some fish may never encounter these medications in their life, others get treated quite heavily.
Some common symptoms that are seen in response to such situations are often muscle tremors or convulsions, which are usually attributed (sometimes incorrectly, sometimes correctly) to hypocalcemia. Other toxins can lead to hepatic or renal damage, which can show symptoms usually unrelated directly to the initial toxin. Kidney damage, for instance, often winds up symptomatically as, again, muscle tremors, because pro-vitD3 is converted to vitD3 in the kidneys. Without vitD3, calcium isn't properly metabolized and muscle tremors ensue. Unthorough examination of the animal will diagnose the condition as resulting from lack of proper nutrients in the diet, when in fact the diet may have been fine but contaminates led to organ damage which led to symptoms that are frequently associated with something entirely different mainly because of their frequency in patients. Afterall, how often have we seen muscle tremors and immediately jumped to the conclusion of insufficient calcium in the diet or lack of UVB exposure?
When it comes to fish, my advice is if you wouldn't eat it yourself, you shouldn't feed it to your animals either.

Well there are alot of things that my waterdragons eat that I wouldn't eat myself! LOL! but I agree, that one problem with feeders in general is that you have no idea what contaminates they are exposed to. Like you have said, feeder fish could be exposed to a number of medication, some of which use heavy metals, or other toxins that end up being stored in the fat or muscle of fish. Likewise feeder rodents are often raised on feeds that can contain dangerous levels of fat soluble vitamins, etc. Insects are often fed hormones to increase their growth and many from petstores have little in their stomachs besides newspaper. In general, you are far better off if you raise your own feeders, whatever they maybe. I certainly have seen a difference in the health of my animals when I have done so. As far as parasites go, most herps naturally carry a parasite load and it is usually kept in check, only when stress occurs does it get out of control. One is probably better off worrying about stress then new parasites getting into the diet, however, I would still avoid feeding anything I knew was infested. Even host specific parasite can cause damage, sometimes even more damage then what they would do it their specific host. Toxoplasma gondii for instance has as its specific host cats and rats, but occasionally, it ends up in people were it can cause miscarriages and has been linked to schizophrenia.