Starfish Aquarium
January 19, 2007 8:13 PM   Subscribe

What animals are needed in an aquarium to keep sea stars? What size tank?

We'd like to start a saltwater aquarium (I have c. 15 years freshwater experience with larger tanks) for the purpose of keeping sea stars. We were thinking:

-acrylic tank
-live rock, live sand
-protein skimmer
-refrigeration unit

Our question is: what animals do we need to cohabitate with the sea stars to keep them healthy and happy? At the local Aquarium of the Bay, they feed them daily by hand - chopped up fish and squid - with only a few sea cucumbers living with the many sea stars.

Are other invertebrates/fish are necessary to keep them happy? They appear to eat snails, corals and urchins, so we should probably stay away from those (except for supplying prey). Do sea stars even need fish?

How large should the tank be to accommodate a few hand-sized sea stars?

posted by stewiethegreat to Pets & Animals (6 answers total) 2 users marked this as a favorite
Since it's been a few hours and no-one's chimed in, I'll tell you what I know :

Sea stars (starfish) - in fact, pretty much all the echinoderms - are either generalist feeders or scavengers. As such, they'll eat pretty much any meat/vegetable marine mix. Fish will be pretty safe (starfish are not fast animals, after all!), but certain fish (wrasse, some of the damsels, etc) will have a go at stars, and almost anything will try the occasional munch on the more feathery varieties.

I like the little yellow / bumblebee gobies myself - inoffensive, won't eat anything else you care to keep, and 6" of personality packed into 1/2" of fish!

Corals may / may not be a problem; it depends on the corals. My guess is that the soft corals (leather, dead man's hand, etc) would be better than the hard corals.

You don't really need anything to co-habit with stars, but some things will help. It's all about keeping the water quality high. Invertebrates (basically anything you're likely to keep bar fish) in particular need are picky about water quality. A couple of small fish can in fact help this, as does keeping other, more mobile, scavenging inverts like shrimp. Add in the things that filter-feed on tiny scraps, like soft corals, feathers, etc, and it's easier to keep a good balance going. The ammonia/nitrogen cycle in a marine tank is much slower, more complex, and more critical than in a freshwater tank.

I really hesitate to get into the filtration requirements - it's almost guaranteed flame-war territory between marine aquarists - but here goes.

Biological filtration is the key. Personally I'm not convinced live rock is enough, even in a low-load situation like a purely invert aquarium. A good trickle filter filter (in addition to live rock) will provide plenty of extra capacity, which comes in handy when the inevitable tank-swing (due to decomposing uneaten food, temperature variations, or a dozen other things) happens.

There's a good arguement that running a protein skimmer too much on an invert-based tank is a bad thing - it takes out the fine food the filter feeders rely upon - and I tend to agree. I certainly wouldn't start with one, unless you're extremely clumsy about feeding, but I've run one for a few days every week or two once a tank has established itself.

(In case you didn't know, it can take 4~6 weeks or more to start up and "season" a marine tank. The method you use to start the tank and get the nitrogen cycle going determines to a large degree when and in what order you stock it.)

The rest you need to know - how to start a tank up and get the nitrogen cycle going, what fish / inverts / corals will live happily together, etc, is best answered by a good petshop. Shop around, listen to them all, and decide what makes sense to you, is the best advice I can give.

Oh, and instead of corals, how about corallimorphs? Look as good or better than most easily kept corals, and the damn things are pretty much unkillable - they can stand a slightly crook tank for weeks, just staying all shrunken and shrivelled, then bloom wide open and reproducing when everything's happy again.

(If you look carefully at a display tank in a pet shop, you might notice that - apart from one or two display specimens - they usually don't actually have many corals. What they do have a lot of are corallimorphs.)

FWIW, I kept a mixed marine tank - fish, corals, and inverts - for about 10 years, up until 5 or 10 years ago. I never actually kept starfish - but I'd buy one every few weeks to feed a couple of Harlequin shrimp I had. The only thing the cute little buggers eat are the legs of Linckia starfish.
posted by Pinback at 3:35 AM on January 20, 2007

Oh , and I meant to mention about tank size. With marine tanks being all about water quality, the bigger the better - more water means more of a buffer against variations in temperature, water quality, etc. The general rule-of-thumb I've always heard and stuck to is nothing smaller than 200L, which equates to about a 2 1/2 foot long tank. Google tells me that's around 53 US gallons.
posted by Pinback at 3:44 AM on January 20, 2007

(Damn - 4 foot!)
posted by Pinback at 3:48 AM on January 20, 2007

sea stars are detrius feeders, so what you feed your other stuff, will help them.

They can be surprisingly sensitive as well, make sure your tank cycle is complete, parameters are good and I would personally add them to an established tank.

I love Linckia (blue stars) but damn they are hard to keep. I lost 2 of them despite having an established tank, and have read others have had problems as well.

Also, sand stirrers will decimate life in your live sand as well, but keep that looking good.

I am going to disagree about the trickle filter thing, unless you remove the bio balls. They are nitrate traps. Replace the bioballs with live rock (crushed even, fragments, etc) and they will spring to life. The bioballs will also have life in them (little stars, pods, etc) but I Dunno, seems like live rock is the best way to go. like a previous poster said, move slowly. Let the tank take care of itself and try to avoid to meddle and use technology to solve every problem.

Anyway, I am going to be moving my current 50g to a cube here this week and am planning on doing an invert tank as well. Should be fun - enjoy having something other than just fish!
posted by evilelvis at 7:05 AM on January 20, 2007

oh and I want to mention something about the protein skimmer. I am a miserly bastard when it comes to electricity usage and while I have run 3 brands of skimmers (Seaclone yea yea blergh, Aqua C remote and the Coralife Superskimmer which are all reasonably priced but not super high end skimmers) I have since removed it. Stuff is _thriving_ now, because all that filter feeder stuff floating around is being put to use. I probably will never ever have a tank of the month but I also am not stuffing my tank full of SPS and a bazillion fish.
posted by evilelvis at 7:08 AM on January 20, 2007

err Aqua C Remora. The Sea cloned sucked. Coralife SS is decent and used a lot by people in the hobby but all 3 don't compare to "real" skimmers. Anyway...there are a billion ways to keep a salt tank, the key is to just go slow!

Ok last post I swear...
posted by evilelvis at 7:09 AM on January 20, 2007

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