Donax “Bean,” Clams in Refuge?
- Thread starter SteveMM62Reef
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No hands-on experience, but some info:
SteveMM62Reef
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I collected them in the Carolinas. I’m not from Orlando. I absolutely do not go to Florida, have a crazy relative, that’s tried everything she can to get an arrest warrant on me, in Florida.
Ah, yeah that's just left over from the thread my quote is from - the clams you have are most likely Donax variabilis, and their care is detailed in the quote I posted.
Sharing it again here:
"The information below is specific to D. variabilis (the most common), but I would assume it would be at least somewhat applicable to the other two species as well:
Lifespan seems to be anywhere from about 8-18 months on average, with some specimens living possibly as long as 3 years.
They stay very small - generally less than 2.5cm (1 inch)
They’re filter feeders, and it seems phytoplankton is ideal for them (specifically a blend of Isochrysis spp. and Chaetoceros spp., but, from what I can find, any phyto 20 microns or less would likely be of benefit - particularly Dunaliella and/or Tetraselmis, possibly Pavlova too; not as much Nannochloropsis). I’m not sure what the specific ratio of the blend should be, but I would assume (possibly erroneously) 1:1.
They should be able to spawn on the Isochrysis/Chaetoceros blend if you slowly (likely over a few days - the info I found is lacking in specifics on the timeframe, but they noted sudden changes don’t work) raise the temperature by 2-3 degrees Celsius (a change from 75-81F or 76-82F, for example, over the course of a couple of weeks or so would likely do it relatively safely)."
As was also noted in the quote above:
"Fair warning, though, these guys can be a vector for flukes (the kind that can kill fish), so that is something you will want to watch for. I’m not sure what an effective treatment would be for any infected bivalves, so I’d refer you to the disease forum here on R2R if that turns out to be an issue."
I don't know, unfortunately. Maybe @Jay Hemdal would have an idea, but - if not - you could just fallow them and that should allow the flukes to die off before they can have a chance to infect the fish.
Jay Hemdal
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If the type of fluke transmits vertically through the food chain, then it is a "digenean". These have such specific host requirements that I don't think they would be an issue. Many of the infections require a gastropod, a fish and a bird to complete their life cycle. I think there are some digeneans that go between mollusks and fish, but if the clams die out, the flukes would also.
I tried keeping this genus many years ago and they didn't thrive. I didn't specifically culture algae for them, and I'm guessing they need that. It also is unknown to me if they are so developed for living in the surf zone, can they even adapt to a static aquarium?
Yeah, they're known to host three different species of digenean trematodes; I've read reports that they may transmit a monogenean trematode as well, but looking into at least one of those claims a little further, it may be a misidentified digenean (Lasiotocus choanura specifically) as it has two eyespots that I can see - good to know.
From what I've read, they can adapt to a static aquarium (though they seem to typically be kept in downwelling/upwelling aquaria), but they're very short-lived (lifespan estimated in months, not years) - they've been able to breed a number of the species (D. variabilis, D. trunculus, D. obesulus, etc.), but they're typically maintained at low temperatures (~64-67F; with temps going up to ~79F max [typically still lower] to induce spawning) and do require phytoplankton. The larval rearing has been done before, but the reported survival rates have been relatively poor (~5-10%), though the rates go up if they're left in the tank with the broodstock bivalves to ~20-31%, so they seem to have specific needs as larvae (they seem to be touchier about which phytos they get adequate nutrition from than many other bivalves).
This got me looking a bit more at their diet (I apparently neglected to save the reports I'd read at the time of my previous, quoted post about these) - Chaetoceros is typically used as the adult feed; Isochrysis is noted as a poor feed when used as a standalone feed for them. They were able to rear the larvae using a Monochrysis sp., but the report was published in 1969, so it's not entirely clear if it was actually a Monochrysis species or a different algae that has been assigned to a different taxon by now.
The best survival rates I've seen used Isochrysis galbana, Pavlova lutheri, Chaetoceros gracilis, and Tetraselmis suecica in an equal parts blend of the four phytos, but T-iso, Monochrysis lutheri, Chaetoceros calcitrans, Chaetoceros mulleri, Tetraselmis chuii, and Skeletonema costatum may confirmedly be used as well. It seems to take about 3-5 weeks for settlement (dependent on species, temperature, etc.), and another ~3 months [Edit: whoops, forgot to finish this statement] for them to grow large enough to be removed from their grow-out tanks (they keep growing pretty much permanently from what I can find).
That said, these are noted for adapting poorly to new conditions for ~1 month; if they survive the first month, they should adapt fine with proper feeding.
References:
(Edit: The Ingenta Connect link above is no longer cooperating, but here's the paper from a different source
(These last two are good, especially the last one, but they're in Spanish - sorry.)
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SteveMM62Reef
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Found out these are Coquina Bi-Valve Clams.Donax variabilis. With all I had to do to get ready for our Vacation, I didn’t bring my Seashore Creatures Guide, Bucket, Jars or Pumps. Also Collected Sargassum, I’m going to see if my Tangs will eat this, if so will blender and freeze it. Also picked up some Deadmans Finger Macro Algae “Codium.” Will try and root it. First day found some Finger Sponge, but had no way of collecting it. BTW, If you want to Beach Comb, Collect, the National Audubon Society, Field Guide to North America Seashore Creatures, is indispensable.
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