Okay, a quick look through your list confirms that all of the fish you are considering generally do well with seahorses in my experience, providing the aquarium is large enough. So the quick answer to your question is that all of the fish below should make good tankmates for seahorses providing your community tank is of adequate size.
Aggression towards the seahorses is unlikely to be a problem with any of the fish on your list, Kayce. I have never experienced a problem of any kind between seahorses and blue/green chromis, purple firefish, Rainford’ s gobies, pistol shrimp/goby symbionts, or Mandarin dragonets. The flasher wrasse and Midas blenny will almost certainly totally ignore the seahorses, but may compete with them for frozen Mysis. Nemo clownfish (Amphiprion occelaris) are by far the best clownfish species to keep with seahorses — and the only ones I would recommend — although they will be competitors at mealtime.
In short, Kayce, I do not foresee any insurmountable obstacles with any of the fish you are considering keeping. Some of them will compete with the seahorses for the frozen Mysis, but that problem is easily controlled by target feeding the seahorses.
Providing the aquarium is large enough, the activity level of the fish, whether they are fast swimmers in midwater or active fish that busily orient to the bottom, is usually not an issue. For example, I know many hobbyists with large community tanks that keep Ocean Rider seahorses successfully with various butterflies, tangs, wrasse, and dwarf angelfish with no difficulties.
For example, here’s an example of such a mixed community that’s proven to be very successful for another home hobbyist (Susan, who is one of the original members of the Ocean Rider: discussion forum), Kayce, and as you can see, her seahorses thrive amidst the number of active fish that are strong swimmers.
“My tank is a 150 gallon tall (3 1/2 feet) with a 50 gallon sump system giving me 200 gallon volume of water!! a good amount of live rock (approximately 125 pounds)! I use Aragonite sugar sized oolitic sand. For filtration and circulation I use a Rio 3500 with a backpack overflow and I have a protein skimmer, UV sterilizer, two sponge filters, a magnum 350, an emperor 400 and I use purigen — NO carbon.
I house approximately 30 sea horses along with a lot of snails both turbo grazers and Nassarius for detritus! I keep two scooter blennies, several wrasses, 3 butterfly fish, and a naso and kole tang! I also have 3 clowns. Usually you don’t see sea horses in a tank with fish and normally this might be a problem! However, I have ONLY … captive raised Ocean Rider sea horses and they were in the tank first and I decided to try the fish with a second tank cycled and in the wings to move the fish to should it have been an issue! Well the … horses were not ill effected at all — in fact the truth be told the sea horses were somewhat bullish with the fish (Susan, 2003).”
If your tank will be housing a pair of dragonets, Kayce, you want an aquarium that is large enough to provide them with natural fodder to graze on between meals. I absolutely love the psychedelic coloration and peaceful nature of Mandarin dragonets! There’s no disputing that they are gorgeous little fishes and make ideal tankmates for seahorses in the right type of setup. They are docile, slow-moving, passive fish that are beautifully marked and very deliberate feeders. And they are quite hardy fish PROVIDING they can be fed properly. They have a heavy slime coat that seems to make them quite resistant to protozoan parasites such as Cryptocaryon irritans.
But, as you know, in order to do well, mandarins need a large, well-established aquarium loaded with live rock or live rock rubble that’s teeming with copepods and amphipods. Mandrins must have continuous opportunities to graze on suitable live foods or they generally slowly waste away and starve to death. In the right system, they can thrive, and will often learn to take small pieces of frozen Mysis, but they do best in well-established reef systems or aquariums with at least 1 pound of live rock or LR rubble per gallon, a mature sand bed, and a refugium that can continually replenish the pod population in the tank. Those are typically the conditions that are necessary to assure they have adequate suitable live prey. .
Mandarins are bottom feeders that normally do not take food from the water column, so select an aquarium with a large foot print that can accommodate plenty of live sand, small pieces of live rock, live rock rubble, and macroalgae.
In other words, Kayce, seahorses and mandarin dragonets make terrific tankmates and enjoy the same kind of aquarium conditions, but your ability to feed the dragonets properly will determine how successful they will be in any given setup.
The shrimp goby and red banded snapping shrimp should also make excellent tankmates for your seahorses, and the symbiotic relationship between the goby and the pistol shrimp is fascinating to watch. Various species of gobies, such as watchman and shrimp gobies, will form mutually beneficial relationships with pistol shrimp, in which the shrimp’s burrow provides a safe home for the goby, which in turn acts as a guardian for his pistol shrimp room mate. Once they set up housekeeping together, the goby will act as a sentry or guard dog for the pistol shrimp, warning him of danger and escorting the nearly blind pistol shrimp back to the burrow if the pistoleer strays too far from the opening. (Pistol shrimp have very poor eyesight and make their way around by touch using their antennae and by scent, so, with its sharp eyes, the goby can detect danger from much further away than the shrimp could.) That’s why such gobies are often called "watchman" gobies, Kayce — because they watch over their pistol shrimp partners. In return, the goby gets a safe place to live, since it can retreat into the shelter of the burrow whenever danger approaches. Both the goby and the pistol shrimp are very timid, and I have never known them to bother seahorses in the least.
So feel free to enjoy the fascinating relationship between him and the shrimp goby, Kayce. Unlike mantis shrimp, pistol shrimp do not grow very large. Some species stay small, perhaps only 1/2 inch long, while others get to be 2-3 inches long. Their diet is omnivorous. They feed on algae, scavenge for leftovers, and prey on small crustaceans and worms such as Gammarus and other amphipods. They defend themselves with the concussion from their pistol shots, and can also overwhelm larger prey in that manner, if necessary. But your red banded pistoleer will be primarily living off algae and leftover flake food or Mysis shrimp.
This is what I normally advise home hobbyists regarding clown fish, Kayce:
Clownfish meet many of the criteria for suitable tankmates, but should generally be regarded with caution (Giwojna, Feb. 2004). Most species, such as Tomato Clowns (Amphiprion frenatus), Maroon Clowns (Premnas biaculeatus), and Skunk Clownfish are surprisingly aggressive and territorial, and should be shunned on that basis. Others do best when keep with anemones, which are a threat to seahorses. All clownfish are prone to Brooklynella and Marine Velvet (Amyloodinium), and should be considered Ich (Cryptocaryon irritans) magnets as well (Giwojna, Feb. 2004). The only species I would recommend as companions for seahorses are Percula Clowns (Amphiprion percula) and False Percula Clownfish (A. ocellaris), and then only after a rigorous quarantine period (Giwojna, Feb. 2004). Captive-bred specimens are best and the cultured A. occelaris or percula are not normally territorial or aggressive toward seahorses.
Since your pair of clown fish are healthy and have been living with you for some time, your Amphiprion occelaris should be safe to keep with your seahorses, Kayce.
In summation, here are my assessments for the various fish on your list:
McCosker’s Flasher Wrasses (pair, may add another female or two) — generally peaceful toward seahorses, and their activity level and agility as fast swimmers will not be disruptive for the seahorses at all in an aquarium of sufficient size; however, the wrasse will compete for frozen Mysis so be prepared to target feed the seahorses.
Rainfordi Goby — no problem, completely safe with seahorses. A big thumbs-up.
Dragonet (pair) — no worries as long as you can feed the dragonets properly, which will require a large, well-established aquarium with plenty of pods.
Clownfish pair (Ocellaris) — captive bred Amphiprion occelaris usually do well with seahorses, but can become pests at feeding time, so be prepared to target feed your seahorses.
Purple Firefish (pair) — excellent choice for a seahorse tank; beautiful, peaceful fish that like to show themselves and will not compete for food with the seahorses. Ideal tankmates for your ponies.
Yasha White Ray Shrimp Goby (pair + red banded snapping shrimp) — will not bother the seahorses and their symbiotic relationship is extremely interesting to observe. Go for it!
Midas Blenny — usually does great with seahorses with the rare exception of an occasional "rowdy" individual. Your Midas blenny should get along fine with the ponies as long as you target feed the seahorses.
3 blue/green Chromis — another excellent choice for a seahorse setup. The chromis will ignore the ponies and add color and activity to the upper half of the aquarium.
All things considered, Kayce, I can see no reason not to include the fish listed above and your new seahorse setup after you make the move across country. I do not anticipate any problems providing one of the fish proves to be the rare "exception to the rule."
However, you must be willing to feed the seahorses properly when keeping them with other fishes in order to assure that the seahorses get enough to eat, as discussed below:
Feeding Seahorses in the Community Tank
When keeping seahorses in an appropriately elaborate environment, it is imperative that you feed them properly! Domesticated seahorses thrive on enriched frozen Mysis as their staple, everyday diet. But the worst thing you can do when feeding the seahorses in a intricate reef or live rock environment 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 (Giwojna, 2005). There it will begin to decompose and degrade the 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 begun to spoil. Either outcome can have dire consequences (Giwojna, 2005).
The best way to avoid such problems is to target feed your seahorses or set up a feeding station for them. See my online article in Conscientious Aquarist for a detailed discussion explaining exactly how to set up a feeding station and train your seahorses to use it:
Click here: Seahorse Feeders
Personally, I prefer to target feed my seahorses instead, and handfeeding is my favorite technique for this. The individual personalities of seahorses naturally extend to their feeding habits. Some are aggressive feeders that will boldly snatch food from your fingers, while some are shy and secretive, feeding only when they think they’re not being observed. Some like to slurp up Mysis while it’s swirling through the water column, and some will only take Mysis off the bottom of the tank. Some are voracious pigs that greedily scarf up everything in sight, and some are slow, deliberate feeders that painstakingly examine every morsel of Mysis before they accept or reject it. Some eat like horses and some eat like birds. So how does the seahorse keeper make sure all his charges are getting enough to eat at mealtime? How does the hobbyist keep the aggressive eaters from scarfing up all the mouth-watering Mysis before the slower feeders get their fair share? And how can you keep active fishes and inverts with seahorses without the faster fishes gobbling up all the goodies before the slowpoke seahorses can grab a mouthful?
Target feeding is the answer. Target feeding just means offering a single piece of Mysis to one particular seahorse, and then watching to see whether or not the ‘horse you targeted actually eats the shrimp. Feeding each of your seahorses in turn that way makes it easy to keep track of exactly how much each of your specimens is eating.
There are many different ways to target feed seahorses. Most methods involve using a long utensil of some sort to wave the Mysis temptingly in front of the chosen seahorse; once you’re sure this has attracted his interest, the Mysis is released so it drifts down enticingly right before the seahorse’s snout. Most of the time, the seahorse will snatch it up as it drifts by or snap it up as soon as it hits the bottom.
A great number of utensils work well for target feeding. I’ve seen hobbyists use everything from chopsticks to extra long tweezers and hemostats or forceps to homemade pipettes fashioned from a length of rigid plastic tubing. As for myself, I prefer handfeeding when I target feed a particular seahorse.
But no doubt the all-time favorite implement for target feeding seahorses is the old-fashioned turkey baster. The old-fashioned ones with the glass barrels work best because the seahorses can see the Mysis inside the baster all the way as it moves down the barrel and out the tip. By exerting just the right amount of pressure on the bulb, great precision is possible when target feeding with a turkey baster. By squeezing and releasing the bulb ever so slightly, a skillful target feeder can keep a piece of Mysis dancing at the very tip of the baster indefinitely, and hold the tempting morsel right in front of the seahorse’s mouth as long as necessary. Or if the seahorse rejects the Mysis the first time it drifts by, a baster makes it easy to deftly suck up the shrimp from the bottom so it can be offered to the target again. In the same way, the baster makes it a simple matter to clean any remaining leftovers after a feeding session. (You’ll quickly discover the feeding tube is also indispensable for tapping away pesky fish and invertebrates that threaten to steal the tempting tidbit before an indecisive seahorse can snatch it up. And it’s great for tapping on the cover to ring the dinner bell and summon the diners for their gourmet feast!)
In short, target feeding allows the hobbyist to assure that each of his seahorses gets enough to eat without overfeeding or underfeeding the tank. And it makes it possible to keep seahorses in a community tank with more active fishes that would ordinarily out-compete them for food, since the aquarist can personally deliver each mouthful to the seahorses while keeping more aggressive specimens at bay.
The key to keeping active specimens like firefish or cleaner shrimp successfully with seahorses is to feed the other fish and inverts with standard, off-the-shelf aquarium foods first, and once they’ve had their fill, then target feed or hand feed the seahorses.
Best of luck transporting your fishes cross-country, Kayce!