Dear Carrie:
No, it’s not customary for females to go off their feed when they are hydrating eggs. Seahorses are fractional spawners. Females maintain a spiraling assembly line of developing oocytes (egg cells) at all times, only a portion of which are fully mature and are released at each mating (Vincent, 1990). This differs from the reproductive strategy of most fishes, which are multiple spawners that release all their eggs each time they mate and then start over, maturing an entirely new clutch of eggs from scratch for the next spawning.
The structure of the ovaries is unique to syngnathids. They are paired organs, which join to form a single oviduct (the seahorse’s version of a Fallopian tube) just before the urogential pore (Vincent, 1990). Oocytes spiral out from the center of each ovary, creating a coiled sheet of developing eggs at differing stages of growth (Vincent, 1990). The earliest or primordial eggs arise from the germinal ridge that runs the entire length of the ovary, and lie at the center of the coil from which they spiral out as they develop so that the fully mature eggs are the furthest from the center of rotation (Vincent, 1990). Roughly 20-25% of the outermost eggs in this ovarian assembly line are mature, ready to be discharged during ovulation and deposited with the male (Vincent, 1990). Thus, fully 70-75% of the female’s developing eggs are retained in the ovaries after mating, so a new clutch of eggs will mature relatively quickly and lie in readiness for the next mating cycle.
Seahorse ovaries are always active, busy creating and developing new eggs (oogenesis), forming the yolk (vitellogenesis), and resorbing any mature ova (atresia) leftover after mating or at the end of the breeding season (Vincent, 1990). Eggs in all 4 stages of development can be found in the ovaries throughout the year, so mature females that are actively breeding normally have an excellent appetite. As you can imagine, they need all the calories they can get to keep their ovarian assembly line running smoothly.
So when a mature female goes off her feet, the loss of appetite can be a warning flag. Most often, they will resume their usual ravenous eating habits again by the next meal when they eat lightly for whatever reason during the previous feedings. If not, if your female who is normally such an aggressive eater continues to need coaxing to eat, suspect a problem of some sort. In that case, Carrie, I would check all your water quality parameters and then perform a water change regardless of how the water chemistry checks out to see if that makes a difference. Many times a water change is all that’s necessary to stimulate a flagging appetite.
Best of luck with all your seahorses, Carrie! Here’s hoping your female is soon eating like a horse again!
Respectfully,
Pete Giwojna
Ocean Rider, Inc. is an Organic Hawaiian-Based Seahorse Aqua-Farm & Aquarium that Follows Strict Good Farming Practices in Raising Seahorses and Other Aquatic Life.
