Re:crabs and peppermint shrimp/I Harry pregnant?

#4769
Pete Giwojna
Guest

Dear Marilyn:

You’re most welcome! It’s great to hear that your new Mustangs are doing well and getting along splendidly with your H. fuscus ponies.

It’s difficult to say whether or not Harry is pregnant, but becoming more sedentary and a little less interested at mealtime are a couple of the subtle behaviors often displayed by broody males. Here are some of the other signs to look for if you suspect that Harry may be pregnant, Marilyn:

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There are a couple of obvious tip offs that indicate mating has occurred you should keep in mind.

First of all, when a female ripens a clutch of eggs in preparation for mating, her lower abdomen becomes noticeably swollen, particularly around the area of the vent. When she subsequently mates and passes her eggs along to the male, she may then lose up to 30% of her body weight as a result. So if you notice that Bernice has slimmed down dramatically at the same time Harry’s pouch has become enlarged, that could be an indication of a successful egg transfer.

The other rule of thumb to keep in mind is that if a stallion’s pouch remains enlarged for more than three or four days in a row, there is a good chance that an egg transfer may have taken place rather than that the male is simply showing off for the females by pumping up his brood pouch.

In addition to these obvious signs, there are also some more subtle behavioral changes that can alert and attentive aquarist to the fact that his male seahorse may be pregnant. Gravid males often behave somewhat differently; as their pregnancy progresses, they are less mobile and become real home bodies, since they cannot expose their developing brood to any unnecessary risks. They tend to hole up and may even go into hiding; they may go off to feed and miss a meal or two or fail to show up at the feeding station now and then.

Here are some other indications to look for which indicate mating has occurred and that the pregnancy is progressing normally:

Indications of Pregnancy.

If you witness the copulatory rise and exchange of eggs there is no doubt that mating has occurred and, knowing the date of conception, you can confidently begin the countdown toward the maternal male’s delivery date. Knowing approximately how long the gestation period will be allows plenty of time to prepare nursery tanks, set up a battery of brine shrimp hatcheries, and culture rotifers and ‘pods for the insatiable fry.

But what if you missed the big moment? How do you proceed if you missed the actual mating and transfer of eggs, and you’re not sure if you will soon be dealing with a gravid male and hordes of hungry newborns?

There are no aquatic obstetricians, underwater ultrasounds, blood tests or over-the-counter pregnancy tests to perform, and I shudder to think how one might go about collecting a urine specimen to dip! No worries. Fortunately, there are subtle signs and suggestions that indicate a pregnancy is underway. There are number of changes in the parents’ appearance and behavior to look for. For instance, the male and female will still continue to flirt, but the nature a their displays will change from full-blown courtship to regular greeting rituals.

After mating, in subsequent days the couple will continue to change colors and brighten up when in close proximity and dance together in an abbreviated version of courtship known as the Morning Greeting or Daily Greeting. The pair exhibits the same basic behaviors and maneuvers as when they were courting with one big difference — the male never "pumps" and the female does not "point."

In addition, as the pregnancy progresses, the male’s pouch darkens due to the proliferation of epithelial and connective tissue and the placenta-like changes taking place in the wall of the marsupium, and the pouch gradually swells and expands according to the number of young developing within. The latter is not always a reliable indicator, however. Inexperienced couples often spill eggs during the exchange and a male’s first few broods are often inordinately small. The brood pouch of a male that is carrying only a few fetal fry is hardly any larger than normal, and hobbyists have often been surprised by unexpected births under such circumstances.

On the other hand, an experienced male carrying a large brood can be easily distinguished by his obviously expanding pouch. These mature breeders may carry broods numbering over 1600 fetal fry, depending of course on the species. A stallion incubating hundreds of fry will have an enormously distended pouch by the time his due date approaches.

Gravid males often become increasingly reclusive and secretive as their pregnancy advances. When the onset of labor and birth is imminent, the male will begin to shows signs of distress and his respiration rate will increase to 70-80 beats per minute. The fully developed young become very active and shake loose into the lumen of the pouch shortly before delivery. In some cases, the writhing of the young can be detected through the stretched membrane of the pouch, which causes the male considerable discomfort. He may become restless and agitated as a result, swimming slowly to and fro and pacing back and forth like, well — an expectant father. The fry are usually born in the early morning hours between midnight and dawn, arriving all at once or in multiple batches 24 hours apart.

So if you happen to miss the exchange of eggs, watch closely for the following indications that mating has occurred:

(1) A change in the physical appearance of the parents. The gravid male’s pouch will change from a light opaque color to a dark brown due to the elaboration of the internal structures and thickening of the walls of the pouch. It will enlarge steadily over the next few weeks as the young grow and develop, and the aperture will change from fully dilated to a tightly closed vertical slit. The female’s trunk will change from rotund, full with ripe eggs, to noticeably shrunken and pinched in immediately after the exchange of eggs.

(2) A change in the seahorses’ courtship displays. The pair will continue to flirt and dance and brighten in coloration as part of their Daily Greetings, but the male will no longer pump (no pouch displays) and neither the female nor the male will point. The pair will make no more copulatory rises.

(3) A change in the behavior of the male. He may become increasingly shy and reclusive. Gravid males may go off their feed as the delivery date approaches, missing meals or even going into hiding. When birth is imminent, he will become agitated and distressed and his respiration will increase markedly.

When you notice these telltale signs of pregnancy, it’s time to kick your brine shrimp hatchery into high gear and start some microalgae and rotifer cultures brewing.
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Okay, Marilyn, that’s the rundown on how to determine whether or not you have a pregnant male on your hands. The black c-shaped, curved objects you observed sound like they could possibly be fetal fry or embryonic young, but ordinarily the developing young are not visible. Usually the male keep the pouch tightly sealed throughout the pregnancy, and only opens the mouth of the pouch when delivery is imminent. It is at this time that the developing young shake loose from the lumen into the central cavity of the pouch, and you can sometimes see tiny tails or snouts protruding from the aperture as the male goes into labor. So I am puzzled by the black curved objects that you observed within his pouch; developing young are normally never exposed to the outside world until they are expelled during the birth spasms. Unless he has released some premature young that are undeveloped, I cannot account for the black c-shaped objects that you noticed, Marilyn. If you could possibly provide me with a picture of them ([email protected]) I may be able to figure out exactly what you are observing.

With regard to the new invertebrates, Marilyn, if you have a quarantine tank with inactive biofilter set up, then you might want to consider quarantining the new micro hermits and peppermint shrimp before you introduce them to your seahorse tank to be extra safe. But if you don’t have a quarantine tank with the biological filtration established, then you won’t want to quarantine the new invertebrates — the shrimp will not tolerate the ammonia spikes that would occur in an uncycled quarantine tank, and the risk of the invertebrates introducing anything harmful to the seahorses (or any other vertebrates) is really rather slight.

With snails, decorative shrimp, and other invertebrates, quarantining is not ordinarily accomplished by isolating them in a quarantine tank and then treating them prophylactically with various medications, as is the recommended procedure for quarantining marine fish before they are added to the aquarium. For one thing, invertebrates in general are not susceptible to the same pathogens and parasites that plague seahorses and other marine fishes. If they were carrying any of the parasites that could bother seahorses, it would be as hitchhikers, and that’s unlikely because those same parasites normally cannot survive long without a suitable fish host.

Secondly, snails, shrimp and invertebrates in general cannot tolerate the usual prophylactic measures we apply to marine fishes when we quarantine them. For example, many types of snails cannot withstand hyposalinity let alone a freshwater dip. Nor do they tolerate the usual chemi-therapeutic agents we normally use to cleanse quarantined fish of parasites, such as formalin, malachite green, copper sulfate, dylox, Panacur, praziquantel, Parinox, metronidazole, etc.. So there would be very little we could do to treat snails, shrimp, or other invertebrates prophylactically or preventively even if we isolated them in a hospital tank for an indefinite quarantine period.

So I normally don’t quarantine the snails and hermit crabs for my cleanup crew in that sense. Rather, I screen them visually to avoid snails (or micro-hermit crabs) with telltale fuzzy pink patches on their shells indicating hydroids or that may be carrying nuisance algae. If in doubt, I’ll use a clean toothbrush to scrub their shells clean and then carefully acclimate them to the new aquarium. The risk that the new hermits are peppermint shrimp could introduce anything harmful to the seahorses is about the same as the risk from feeding them with live foods such as adult brine shrimp or ghost shrimp from your LFS, and you would not ordinarily quarantine such live foods before offering them to your seahorses.

Best of luck with your seahorses, Marilyn! Here’s hoping that Harry is carrying a brood of developing young for you and Bernice.

Respectfully,
Pete Giwojna


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