Urchins in large fish only systems?

Discussion in 'Tridacnid and Inverts Forum' started by Aaron L., Jul 16, 2017.

  1. Aaron L.

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    Hi all. I have a fish only system without a CUC. Currently stocked with a couple of big eyed squirrels, large volitan lionfish, some damsels, and a couple of morays (dragon and tessellated).

    Any reason I couldn't keep urchins to eat some of the algae? Anything else I can keep in this type of system to help do some maintenance?
     
  2. OP
    Aaron L.

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    I should add : what are acceptable nitrate levels?
     
  3. capman

    capman I contributed!
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    Urchins typically need a lot of food, and if they are not getting enough of appropriate algae from your tank, you might want to supplement their diets. Some species will readily accept a variety of foods, others seem to only want to graze algae off of rocks.

    Otherwise, I see no reason why urchins should be a problem, or why they should have problems. This is a broad blanket statement though, sort of ignoring the fact that there are many species of urchins with different habits (though I guess the number of species available in the aquarium trade is more limited).

    Note that some urchins are actually predaceous, and don't necessarily graze algae much. Pencil urchins are an example. Pencil urchins will eat a variety of sessile invertebrates, they will eat other urchins sometimes (I've had this happen), I've had them eat sea stars (clamping their thick spines on the seastar to hold on to it), and I had one catch and start to eat a sleeping dwarf angel once (had just been introduced to the tank, so its possible it died and then got found, but the urchin was holding on tight, and I have little doubt that they could grab sleeping fish like this).

    So, personally, I only keep pencil urchins in situations where they can't catch and eat other animals, but otherwise I think urchins should be great additions to your tank.

    As far as nitrates are concerned: I think if your fish are happy most urchins probably will be too.
     
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  4. infinityends

    infinityends Senior Member
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    One other thing to consider although most would just suggest a hospital tank. If you don't already have other inverts like snails and shrimp in the tank. If the system is truly fish only. You have the option of treating the entire system directly with copper in the case of an ich or other parasite outbreak.
     
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  5. marty9876

    marty9876 Something funny
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    I tried them, didn't work out for the long term- they withered away.
     
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  6. capman

    capman I contributed!
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    I guess fish only tanks don't generally have such bright lighting as reef systems, so maybe algae don't necessarily grow as rampantly? Or possibly the right sorts for the urchins don't grow well.

    Regardless though, I really think at least some of the urchins need supplemental feeding to do well. (And even some of the algae grazers love animal-based foods when they can get them - our 5 or 6 year old longspine urchin loves to eat the tails of the big shrimp I buy to feed crabs, anemones, the horseshoe crab, etc, and it tends to spawn when it gets fed well this way). I have some species of urchins that ONLY graze natural algae growths though.
     
  7. marty9876

    marty9876 Something funny
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    There was more than enough green/hair/that junk for him in the tank. Additionally, with my feeding habits he had supplemental feeding a few times a day...:)

    Black long spine was what I tried
     
  8. OP
    Aaron L.

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    I thought most invertebrates were intolerant of high nitrates, but have never thought it was an issue for fish. The nitrates in my fish only are off the charts...the only thing I understood that to cause were algae blooms.
     
  9. marty9876

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    I can't recall if I had my denitrator running at that time or not. Ahh getting old sucks.
     

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