It’s pretty hard to quantify how much your seahorses should be eating because it depends in large extent on the size of the seahorses and of course the size of the individual Mysis they are eating, as well as a number of other factors. But I can tell you that 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 needs to eat fewer shrimp than a pony that’s dining on the tiny Hikari 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, Kelly. 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.)
So if you want to check whether your seahorses are eating well or not, Kelly, don’t look at their profile — examine them head-on and check out their gut. Their abdomens or belly plates should bulge out slightly or at least be flush with their flanks, not pinched in or sunken. In other words, when viewed from the back or from head-on, the cross-section of their abdomens should appear concave "( )" or flush "l l" rather than concave ") (" or pinched in.
In general, it’s a good idea to offer one morning feeding and one mid-to-late afternoon feeding, if possible, but there are no hard-and-fast rules when it comes to easy-to-feed, farm-raised horses. Some hobbyist prefer to give their seahorses two feedings a day, while others prefer to give them their quota of frozen Mysis in one big meal. As long as they get their fill, there is really no right or wrong way to go about this — just do whatever works bests for your seahorses and your schedule.
However, many hobbyists find that their seahorses feed best during the morning, so if you can only feed your seahorses once a day, try to make it a morning meal. Whether it’s their biological clocks, something built into their natural circadian rhythm, or just that they’re simply hungriest shortly after waking up after not eating all night, seahorses do seem to feed more aggressively in the morning, and hobbyists should try to accommodate them, if possible. Breakfast, it seems, is the most important meal of the day for our aquatic equines as well as ourselves.
If you can only manage one feeding a day, DO NOT make it an evening meal. The worst thing you can do is to feed your seahorses late in the day when there will likely still be leftovers remaining at lights out. The uneaten Mysis will begin decaying overnight and put your water quality at risk. Worse still, the next morning, when they are hungriest, your seahorses may discover the bacteria-laden Mysis and snap them up off the bottom. This is an excellent way to spread disease and make your seahorses sick. Feeding your seahorses early in the day, so they have plenty of time to clean up leftovers, is a good way to prevent this. An efficient clean-up crew of scavengers also helps.
It sounds like you have worked out a very sensible feeding regimen in that regard, Kelly. It’s a good idea to give your seahorses a big feeding in the morning when they are hungriest, and then a smaller meal later in the day, which they can easily clean up before lights out.
Just be sure that you don’t scatter-feed frozen foods!. Whether it is a SHOWLR tank, a modified minireef, a seagrass system or a mangrove biotype, a well-designed seahorse setup is a fairly elaborate environment. A certain level of complexity is necessary in order to assure that our seahorses behave naturally (Topps, 1999) and to provide our ponies with plenty of hitching posts and shelter, and enough sight barriers to assure them a little privacy when they feel the need to be alone. Their homemade habitat may thus take the form of a labyrinth of live rock, an intricate arrangement of corals and gorgonians, a well-planted bed of seagrass or macroalgae, or a full-fledged reef face. When feeding seahorses in such intricate surroundings, the worst thing you can do is to scatter a handful of frozen Mysis throughout the tank to be dispersed by the currents and hope that the hungry horses can track it all down. Inevitably some of the frozen food will be swept away and lodge in isolated nooks and crannies where the seahorses cannot get it. There it will begin to decompose and impair your water quality, which is why ammonia spikes are common after a heavy feeding. Or it may be wafted out into the open again later on and eaten after it has gone bad. Either outcome can lead to dire problems.
Using a feeding station or target feeding your seahorses and diligently cleaning up any leftovers afterwards can avoid this. That is absolutely imperative when maintaining seahorses in an appropriately elaborate environment. An efficient team of aquarium janitors and scavengers can also be a big help with the tidying up.
Best of luck keeping our galloping gourmets well fed, Kelly!