Some days you just want to sit on a beach and shoot video of ghost crabs.
For roughly my whole life I’ve wondered why white-sand beaches only have white crabs and black-sand beaches only have black crabs. I figured that every beach started out with all colors of crabs and the seagulls sorted things out… But, get this:
A month later all 7 little Lysmata shrimp are doing fine. Three of them had a netbox to themselves, and two of them were paired up. I didn’t have any trouble with cannibalism, and the shrimp grow slowly but visibly. Food was plankton-based flake food, Wardley shrimp pellets, and frozen krill.
Meanwhile, the parents have gone through another cycle of laying and hatching. I’ve collected a few dozen zoeae which I’m raising in the same manner as before. If they make it to the post-larva I’m planning to try a more free-range approach to raising them and see how they do in larger numbers.
After several failed attempts, I’ve just now succeeded in raising my first peppermint shrimp from egg to post-larva. I took a bunch of photos and videos, and they’re all terrible.
This species has a reputation for being fairly easy to raise, although googling turns up more tales of failure than success. The process I’m using now is dead simple, and I’ve met with success on my first try with these particular parents, so I suspect that the variation in success with captive rearing is a result of a bunch of different species being imported with the same ‘peppermint shrimp’ label. Are my shrimp really L. wurdemanni? I’ll probably never know.
I started out with a paltry number of larva — around a dozen. I have an air-powered plankton collector in the tank with the adults, but also a protein skimmer which I’m sure is snagging most of the hatchlings. I moved half the larva into a 1-liter box with blacked out sides (as per googled suggestions). Those didn’t last long. The other half went into an extremely low-tech, improvised kreisel:
That’s a 2-gallon drum bowl with a bit of bubbling airline in the corner. This worked surprisingly well — shrimp larvae and their brine shrimp food remained suspended in the water column at all times, unlike the larvae in the smaller box who tended to bump around on the bottom.
Here are close-ups of newly-hatched Lysmata, along with a high-speed video of their weird bendy pleopods:
After five days, not much had changed.
A week later, they had changed shape completely. I mistook the longer legs for pincers, but closer inspection shows that they’re back legs rather than forelegs — it seems like they’re used for stability when floating rather than for hunting.
At day 25, the larvae are much bigger, but the body form remains much the same. It’s hard to tell scale from the photos, but they’re in the neighborhood of 10-15mm at this point. They have the same constantly-waving pleopods that they had on day one; the front four pairs of legs look like legs, and the back pair are still those crazy, giant oar-like shapes.
Finally on day 30, one of the larvae changed in a flash into a shrimp. The crazy oars are gone, the pleopods are tucked under the body, and it’s almost entirely adult-shaped. Rather than drifting aimlessly in the bowl, it’s sitting on the back or the sides, occasionally zooming with purpose to a new roost.
For scale, this photo includes a US quarter dollar. The video is completely boring, since now the shrimp is capable of resting.
I still have six more late-stage larvae floating in the bowl. Their sizes vary quite a bit; I’ve no idea how they decide when to metamorphose and settle.
Care is pretty simple. I feed the larvae newly-hatched artemia onec per day, and leave the brine shrimp to swim amongst the Lysmata for as long as it takes to be eaten. Every three days or so I also feed 3-day-old SELCO-enriched artemia. I’ve no idea if the SELCO is essential or not — it’s certainly a lot more trouble. At no point did I attempt to feed larger or different foods.
Every few days I scooped 1/4 of the water out of the bowl and exchanged it with water in the 40-gallon tank that houses the adults. I didn’t attempt to vaccuum the bottom of the bowl — some debris accumulated but it doesn’t seem to do any harm. A light shining on the bottom of the bowl keeps the larvae down low to reduce the chances of them getting scooped out during water changes.
There’s no direct light over the bowl. Other reports complain of larva getting trapped in biofilm along the edges of the container; I didn’t see anything like this, possibly because there wasn’t enough light for biofilm or possibly because the circular current prevented larvae from resting on the glass.
None of the regimen was very compulsive. I missed days of feeding here and there, and two or three times a breaker tripped and the bowl was without aeration for half a day at a time.
The one post-larva is now inhabiting a much-too-big net breeder in the parent’s tank. I’m hoping to keep the young adults separate from one another to avoid cannibalism during molting… we will see how many more I get, and if raising them after metamorphosis is harder than rearing them before.
UPDATE, 2015-09-05: Now six of the seven larvae have settled. All the tiny shrimp are in a long row of tiny net breeders, and all are still alive.
Up close, everything about elephant seals is hideous. They’re smelly, noisy, shapeless and angry, and they can barely wait to abandon their young. They are also terrifyingly gigantic!
Elephant seal skull on left, grizzly bear skull on right
I’m really glad I got to see them, but after the graphic description of their dire, violent, largely hopeless territory-controlling and mating system provided by our tour guide I’m left with a strong impression that if they were to go extinct overnight the sum total of suffering on the planet would be greatly reduced.
It was hot today, so mostly all the seals did was nap. Nonetheless the tension was palpable, with males periodically snapping at each other and bellowing, clearly on high alert despite their torpor.
My favorite (ok, least favorite) part of the tour was when the guide explained that the fights aren’t usually fatal but occasionally seals kill each other. One year, she recounted, a beached female died from a gash in her side. The neighboring males, she explained, were exited by this development because she “couldn’t resist, and had an extra hole.” She wound up the story by saying “Yep, the males only have one thing on their mind.”
At which point one of the guys on the tour (who I must admit I was already not fond of) smirked at the fellow standing next to him and said “Heh, I must be part seal.”
Vanishing-point perspective, illustrated with guppy ponds
There were nearly as many ponds devoted to other livebearers: platys, swordtails, mollys. In the case of the swordtails a single giant pond was subdivided with hanging nets. I’m not sure what the difference is between the different pond arrangements.
These are also all fish that I think of as needing the exact opposite water (hard, alkaline) as tetras, but as best I can tell they don’t mess with the water chemistry for anything but discus.
Discus must not yield to mass-production techniques, because the discus tanks looked just like discus tanks everywhere.
Fish food produced on the premises — rice bran and fish meal
The farm has 55 employees, many of whom live at work. With their kids!
After a short bus trip down a very bumpy road (and past some cows, buffalo, and cornfields) we arrived at the main farm. The main farm is enormous (10 hectares, 24 acres) and runs alongside a canal that provides a year-round supply of fresh water. The water is collected in an elevated reservoir so that all of the tanks and ponds can be supplied via gravity.
One of the major products of this farm is neon and cardinal tetras, and they also raise rummynose and emperor tetras. The climate in Saigon is too hot for tetras to live outdoor in ponds, so most of the indoor space was devoted to row upon row of tetra grow-out tanks. Individual pairs of tetras spawn in tiny glass boxes in dimly-lit rooms, and then the eggs or fry are transferred into smallish tanks to grow up a bit.
Earlier reading led me to believe that feeding the tetra fry would be a big ordeal, with rotifer or moina ponds taking up a bunch of the surface area. Nope! When I asked what they feed the fry Binh just shrugged and said ‘TetraMin. Ground up really small.’ It’s possible that I totally misunderstood his answer, but I definitely didn’t see any food-production tanks other than a few brine shrimp hatcheries next to some baby angelfish in a different building.
I can’t express how very, very many cardinal tetras there were in this room
Rummynose tetras (which until yesterday I thought weren’t bred in captivity)
A stack of breeding boxes, each about 2 liters
Close-up of a breeding box with a bit of netting to keep the parents away from their tasty eggs
Row on row of breeding boxes
Each breeding box has one pair of adults.
There were lots of little tanks with spec-sized hatchlings but I didn’t want to make everyone wait while I sorted out a proper macro photo.
This section of the farm consisted of many tarp-lined ponds full of cut lengths of pvc pipe. The pipe were, presumably, full of adult ancistrus (‘plecos’) of various kinds sitting on eggs, but no adults were visible through the glare.
This technique seems pretty uncomplicated — since ancistrus are good parents they just leave them alone in the ponds and scoop out and sort the young as needed.
Our gracious guide, Binh, perched between catfish ponds