It sounds like you are female has a very healthy appetite, which is a good thing, and as long as you observe a fast day once a week, then I don’t think you need to be concerned about overfeeding her. A seahorse’s appetite is a pretty good gauge of how much they need to eat. When they are really hungry, their actions make it known, and you can offer her an extra snack between your normal feedings, if you wish.
I know how hard it is to resist them when our pampered ponies are begging for food. My Mustangs do the same thing, and it can be quite disconcerting to the seahorse keeper, particularly on the obligatory fast day. The problem with fasting is that my Mustangs don’t seem to realize it’s good for them — that it’s absolutely in their own best interests, essential for their long-term health. Whenever I make an appearance on fast day, they insist on parading back and forth in front of the glass in their greeting colors, begging for a handout. Before my butt hits the upholstery, both of them will be dancing at the feeding station, impatiently awaiting their gourmet shrimp dinner. When it doesn’t materialize, they forlornly abandon their post at the lunch counter, and come up to stare at me through the front glass. When I still don’t take the hint, the female paces back and forth at the front, looking her brightest and most conspicuous, as though trying to attract my attention, while the male reverts to his drab everyday attire and dejectedly resumes his futile vigil at the feeding station. If not for their well-rounded cross-sections, one would think they were dying of hunger, making it difficult to resist their puppy-dog antics. Just sitting there ignoring them makes me feel like a first-class heel. Sheesh–talk about your guilt trips…Dang! I hate fast days.
As you know, the feeding regimen that generally works best for most captive-bred seahorses is to provide each of them with 2-7 frozen Mysis relicta twice a day, enriched with Vibrance, and then to fast your seahorses entirely once a week. In other words, your seahorses should each be eating a total of around 4-14 frozen Mysis each day, depending on the size of the seahorse and the size of the Mysis. But those are just rough guidelines and there is a lot of variation in how much Mysis healthy seahorses eat each day.
A large seahorse naturally eats more than a smaller pony. And jumbo-sized Mysis will fill up a hungry seahorse faster than smaller shrimp. So a seahorse that’s scarfing up king-sized Piscine Energetics Mysis relicta does indeed need to eat fewer shrimp than a pony that’s dining on the tiny Hikari Mysis. (You’ll see what I mean when you get your PE frozen Mysis — it will probably be quite considerably larger than the Mysis you are using now. The feeding guidelines are based on the jumbo PE Mysis, so you can increase the number of Mysis you feed daily accordingly if you are using another brand of Mysis.)
Aside from size, some of the other factors that determine how much a seahorse eats are water temperature, the age of the seahorse, and whether or not it is actively breeding at the moment. The warmer the water temperature (within the seahorse’s comfort zone), the higher its metabolism, and the more calories it needs to eat as a result. Young seahorses that are still growing rapidly typically eat more than mature seahorses that have reached their full growth. As you might expect, breeding pairs that are producing brood after brood every few weeks need to eat a lot because so much of their bodily resources go towards producing clutches of eggs or nourishing a pouch full of developing young.
So don’t get hung up trying to count every morsel every seahorse in your tank scarfs down, gilraen. Just make sure all your seahorses have full bellies at the end of the day, as indicated by their well-rounded abdomens. After a good feeding, the seahorses belly rings should be flush or even slightly convex in cross section when viewed from head on. (We never want to see sunken, severely pinched-in abdomens on our seahorses! Concave belly rings are a sure sign of an underfed seahorse, with the sole exception of a female that has just transferred her eggs.)
Best wishes with all your fishes, gilraen!