large seahorse tank - opinions


New member
Hello all-

I'm just starting to get back into fishkeeping and seahorses have once again captured my interest. I've been keeping freshwater and salt for years and years. I've done a couple of reef tanks, had success with corals, etc. Many (I won't say HOW many) years ago I kept seahorses (dwarfs, "regulars") before we all really knew much about them and I had mixed experiences. Our knowledge has come a long way since then; plus the availability of CB seahorses eating non-live food has made responsible seahorse-keeping a reality. I moved from NY to CA a couple of years ago and am now just starting to get back into fishkeeping. I have a 30 gallon cichlid tank up and running for a couple of months and it's doing fantastic. I also have a pair of blue dart frogs, Dendrobate azureus, set up in 20g habitat and they're doing great. True these are not fish, but it takes the same kind of attentiveness to care for them as it does other challenging, exotic species (I have to culture my own flies for them).

I'm not posting to ask any of the obvious noobie question that can be answered by simply searching posts. My plan is to acquire what I need over a period of time to build a decent setup for a couple of larger seahorses. I haven't settled on a specific species yet, however I would want the species be one the smaller side (and I don't mean dwarfs) - about 5 to 6 inches or a bit more. In any case, assuming this size range of seahorse, I'm looking at different tanks that would be suitable for only TWO (not even interested to breed them, would probably try to get two females when it's time to purchase). I've found an acrylic aquarium that I think would be acceptable and would fit where I want it: it is 16" X 16" X 24" and holds about 26 gallons. True, 16" is not very wide, but because it is cube, it is "deeper" front to back than many aquariums. Also, I thought the 24" height would be good for seahorses. I am probably going to get this tank (unless anyone tells me I'm making a huge mistake!) but I would like to see some experience-based opinions from people here. Thanks!


Things With Stings R Us!
that would be a nice tank for a pair of SH. you could keep erectus, reidi, or barbouri easily in that setup. barbs can be a bit more touchy than the other two species. if you're not interested in breeding, you can keep a same sex tank (if you're squeamish about not raising the fry and removing them).

for aquascaping, i'm a HUGE fan of branchy LR and macroalgae. this gives the SH both hitching and hunting areas for between meal snacking. don't be afraid of flow as long as there are some quieter areas for the SH to rest. of course, you don't want to plaster the SH against the tank wall, but they handle flow a lot better than once thought.

you're on the right track...ONLY get TRUE CB specimens, which means that you'll most likely get them from a reputable breeder or hobbyist/breeder.

i recommend for the three species i mentioned, or Beth (Peka here on RC) for erectus only.


New member
Hey thanks. I've read many of your posts and you always seem to have sound information. Probably reidi or erectus would be the species I will end up selecting. Breeding anything is a time consuming process - the dart frogs I had in NY laid eggs that wet to tads all the time, but the work involved in rearing them was too much.

When setting up something new, I tend to take months to do it slowly and get it right. My cichlid tank ran two months uninhabited and my frog terrarium was three months without frogs.. just plants getting established. So if I don't manage to get this tank for Christmas (which I probably won't!), it will end up being my own after-Christmas gift to myself and then I'll take it from there!


New member
I reread my original post and to clarify the title, I meant a tank for large seahorses (as opposed to dwarfs) not necessarily a large tank.

I've been doing some investigating and I've realized that although the non-standard sized acrylic tank I've had in mind could be a very nice setup, there are some potential difficulties. It is "eurobraced" meaning the opening at the top of the tank is a "window" that is smaller than the perimeter of the tank. I definitely plan to run a chiller and either a canister filter or sump/fuge setup. To do that, these type of tanks need holes drilled through this brace. Additionally, if I wanted on any "hang-on" equipment, that would probably be impossible. Also, although lighting choices aren't quite as critical as they are for a nano or reef setup, there aren't many choices for for tanks less than 24" wide. Buying a standard-sized tank would be more cost-effective and give me more options.

One of the LSF's in my area has a 25 gallon "plant" aquarium that they have not been able to sell for like six months now. I rarely see anything but the usual 10's, 20's, 29's and 55's at any of LFS's, so this would be an opportunity I may not want to pass up. The dimensions are 24" wide X 12" deep X 20" high. After reading about recommended tank sizes on this site and others, I see that there is not a 100% consensus regarding minimal tank sizes. A 29 would definitely be a good choice, but I don't think I have the room for it. (This will be the third and last tank I can fit in my house before it starts looking like Petco here!) I only want to keep TWO erectus or reidi (as recommended by namxas) without any tank mates except for a small, safe cleanup crew and possibly some fan worms. I think this 25 would be ok, especially if I decide to run a sump on it. Does anyone have any opinions? Thanks!


Seahorse Wrangler
25 is on the small side, you're right, but if you have a sump and an efficient nutrient export system; I think you'll be find with a single pair. I know that 30 gallons is often recommended as the minimum for a pair of Erectus or Reidi, but my own experience is that even a 20 gallon is okay as long as you keep up with water changes and monitoring the water quality. A 30 gallon will give you more of a margin for error, but you've got reef keeping experience so I suspect you'll do fine keeping everything in check. Just remember that seahorses are messy fish so they generally require more maintenance to keep their water quality up.


New member
Thanks for the opinion, FishGrrl. I went to this LFS today - Petco (not my first choice for fish, but I purchased many a tank from them.) Turns out that this 25 gallon tank is part of a "package" they would not split up. Here's the ironic thing - half of what's supposed to be included in this package is missing! They've had this tank at least for six months.... I guess they'll have it even longer. Maybe I will try to figure out how to make room for a standard 29g. Another option might be to order an acrylic 25g from In any case, if I do buy locally, it will be from their competitor - PetSmart. I guess it's kinda back to the drawing board for me!


New member
I started with a 20G for my 2 seahorses and honestly, when they were little it was fine but as they just seemed too small.

If you haven't invested in a tank yet, maybe consider something 40G for a pair. I have a 55G for my 4 seahorses (a mix of H.Reidi and H.Barbouri) and I'd not add anymore to that system.