Crabs and bio load

[ZL0gic]

Do small crabs like emeralds or pom poms count towards the bio load of a tank the same way fish do?  I've got a biocube32 cycling and I'm thinking of stocking ideas, but biocubes tend to follow a pretty set pattern of a clown or two, a wrasse, and a blenny or goby.  I'm trying to think of other possibilities for stocking and I'm a big fan of the pom pom crabs

[brandon429]

No. If you had a seneye unit to measure precision changes in nh3 conversion rates you aren’t going to see a difference between a fully cycled tank carrying no crabs or one carrying fifteen hermits (the small ones, large ones may differ) 

 

pom poms included they’re just not a big load we can register. Same for sexy shrimp or cleaner shrimp et al

 

 

these animals do respire and are part of bioloading. But it’s so miniscule even our best devices won’t pick up the small loading. 

[ZL0gic]

Excellent!  Thank you for the reply!  I'm new here, new to saltwater, but I've kept freshwater planted for many years now.  Starting a journal, but wanted to get past the cycle and have more to share.

[Tired]

Invertebrates in general don't count towards bioload for most practical purposes. Except if you got a really big crab, like a full-sized calico crab. Which you probably shouldn't do either way, they're fairly destructive by nature. 

 

When stocking invertebrates, we ignore bio-load and instead focus on their safety and its territory needs. For example, sally lightfoot crabs shouldn't be kept with small fish, and you shouldn't keep 20 cleaner shrimp in a small tank because they will absolutely fight to the death. It's generally best to pick animals that have different niches, when possible. 

[ZL0gic]

I'm really just wanting 2-4 pom pom crabs in addition to CUC.  Stocking this biocube is still up in the air because the pom poms and maybe a starry blenny are the only things I've got in mind so far.

[DaJMasta]

As said, the practical answer is no, but they are animals that produce waste the same as anything else.  Their impact on algae will be negative, eating more than the waste they produce fuels, and they are both low enough energy and small enough body mass as to not make nearly as much of an impact (ammonia production) as fish that are several times heavier and swimming all the time, for example.

As for the pom poms, it's certainly possible for them to be fine, but I don't know if I would go with 3 or 4 and maybe lean on the 2 side.  As mentioned, territory is critical for most creatures in the tank, but especially for ornery ones that walk - inverts.  While there may be plenty of surface area to climb on in a biocube to accommodate several, they will end up preferring certain areas (near the sandbed vs. on the rockwork - in the shade vs. in the light - under an overhang vs. in a small cave), and there's much less likely to be several spots like that in a smaller tank that are sufficiently far from where the other will hang out to be out of the established territory of one.

Rather than several of the same species that would all want to live in the same areas, why not try a few different species to go along with it.  Cleaner shrimp like the underside of ledges to hang out, fire cleaners tend to prefer caves, sexy shrimp like to live on or around anemones, but will walk around on the rock higher up as long as they have somewhere they can scurry to.  Porcelain crabs like cracks and crevices and will only stick out a little to feed.

I'd say same goes for fish when you pick them out, but it can be hard to determine which will do what from just a description or seeing them in a store tank a lot of the time.  Making sure you get fish with, for example, different sleeping space preferences, can be really helpful to keeping the peace.  Some will want to sleep in a cave, some will want to sleep in a burrow, some will just sleep on a rock, and some don't sleep, but if you have too many of one kind (like more burrowers than burrows), you'll end up with some stressed because they just have to lie against a rock on the sand.