Terrible advice Tuesdays (T.A.Tues): Hermit Crabs Are The Natural Polluter
Terrible advice Tuesdays: Hermit crabs add to your bioload. Less hermits means you can have more fish.
The rest of the story: Do hermit crabs produce waste. Very likely. However, the amount of waste hermit crabs produce is small…very small, especially compared to fish. Therefore, reducing the number of hermits you have in your tank so that you can keep more fish is a complete waste of time.
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On the subject of hermit crabs Mark what hermit crabs do you recommended? I’ve hadbad experience with red legged hermits attacking anemones! I’ve heard you shouldwatch all hermits especially when new cause you never know when you might get a rouge bada$$ hermit. is this true or is it mostly the reds? because most sites list them as reef safe?
Hermit crabs are great for a reef tank. You just have to know which ones to have and how to keep them. Reef safe ones are paguriste cadenati, clibanarius tricolor. keep spare shells and they won’t touch your snails…you van have as many as you have food for them in the tank…
I know hermit crabs are great additions to a reef. I have many in my reef tank now. I was asking more about if anyone else has had bad experiences with supposed ” reef safe” hermits? I’ve had to remove red legged hermits personally for picking at anemones and corals. on a different subject I’m sure most people have cleaner shrimp well I’ve also had the same experience with cleaner shrimp everytime I feed my carpet anemone they always picked at it and I even tried to feed them first but they’d still do it. they don’t seem to hurt anything but they do bug the crap out of an anemone for some fish!
the advise seems a ‘bit’ illogical to me? ALL, repeat ALL biological forms produce byproduct. As I’ve mentioned in print before, ALL biological forms add something to the closed system as well as TAKING things out of the closed system. I know hobbyists that brag about having dozens of green emerald crabs in their 120 gallon systems. Along with cleaning crews of a tiny army of hermits, snails of mixed species and misc cleaner species. This is, in the mind, a way to make the environment ‘cleaner’. This is of course not to have a handle on the basic premise of a closed system– It is a limited body of water and all biology will impact it in some way– often it is a matter of degree and there in lies the illusion. JasPR
I didn’t get that he said they don’t have any bio load.what Mark said was they don’t produce enough water to be able to justify talking out hermits to try and add more fish and think your gonna have the same bio load you did before? especially since crabs clean your tank as well.
?? let me try this again and thanks for being patient with me— EVERY living thing produces nitrogenous waste– even your bacteria– in fact that is what nitrite and nitrate ARE. So NOTHING is truly removed from a closed system, it is simply changed from one form to another. A crab is a minor producer– 30 crabs are not. No I can say with some level of confidence that NO ONE knows IF 30 crabs contribute as much to the deterioration of water than say a single damsel. At least in my library I have to technical studies. But it is indeed a limited view to envision inverts ( feeding inverts) as ‘invisible’ in the biological model of a closed system and its deterioration. In fact think about this– many a hobbyist marvels at how their bubble algae or brown sand disappears with the introduction of a massive cleaning crew. Yet the same individual feels that dying algae feeds new algae and that crabs who consume the very same dump nothing back in exchange for their ‘service’ in making undesirable forms ‘go away’. Its not pixie dust that the crabs convert proteins, plant amino acids and sugars to. Just saying—–
I don’t care for them in my tanks. I don’t like spare shells lying around so any snails, which I have very few of, are inevitably assassinated. They’re also too opportunistic, in that without enough food they will find something to eat. I run my tanks too low of nutrients to keep them from snacking on things I don’t want them eating.
I’m going to try a little experiment myself and try a tank populated with rotifers, copepods, bristle worms ..etc. Instead of having an army of opputunistic feeders that will destroy those populations. I also plan on being very selective of the fish that go in. Experimentation is why I love this hobby.
I think most of us understand the nitrogen cycle I guess I just question the benefit you’d get from removing let’s say 20 crabs and putting in like you said a damsel?? I know crabs produce waste but I would have to say I believe they consume more then they produce?
I have always had crabs in my tanks. I like a mix of them too from your basic hermit to the fancy ones. I also have Emerald crabs to help with the clean up. No you do not want to put 100’s in but a healthy amount does more good than harm.
The tank is not a totally closed system, you have to keep in kind that what goes in to an animal does not equal what comes out as chemical waste; energy is converted through metabolism, what the tank members take in gets converted to energy used for the business of living and maintaining their bodies, ultimately given off as heat. The efficiency of this process is the point of this post; fish increase the bioload of a tank to a much larger degree than invertebrates because they metabolize in a different manner and rate. Fish do not process nitrogenous wastes very efficiently because in their natural environment (large open bodies of water) they don’t have to. It would take quite a few crabs to equal the bio load a fish; Mark’s point is that trying to increase the number of fish you can have in your tank by decreasing the number of crabs is not an equation that works out.
that’s what I said workout the big words lol. but even in the closed system everything except nitrate gets eaten to undetectable by something and then most released as no2 through live sand and live rocks out the top of the proshis is another reason we need to maintain high current and flow in our reef tanks just like the ocean. this hobby is about trying to duplicate the ocean and at the same time adjust it to meet the needs of a reef tank witch is the ocean on a MUCH SMALLER SCALE! somethings ate also preference to though cause like stated above some people don’t like hermits in there system and they may have to do a little more cleaning or have a higher rate skimmer but that’s up to them it’s there reef and it wouldn’t be enjoyable if there were exact guidelines for everything to have in your tank or what you do to your tank. most advise in this hobby is an opinion and there’s normally other ways to accomplish the exact same result on different tanks. I personally love having hermits in my tank and think the pros far out weight the cons
A little scientific fact to remember:
Matter is neither created nor destroyed, only transformed…Antoine Lavoisier, father of modene chemistry…Hermit crabes do produce waste, you don’t need an army of them in your tank. Just enough to get to the hard spots you or you shrimp can’t get to. No need to get anal about all of this…
I too have seen the cleaner shrimp grab the fish I feed my anemone. I sure do hate it when they do that and I was thinking of feeding them first to hopefully keep them busy. I figured I would feed the anemone tiny bits so they get swallowed quickly. I was also thinking of using a jar I could put over the anemone while it eats…. its a PITA for sure!
I believe that a clean up crew can not hurt a system any. If I have an extra fish in my system I add extra food for the fish, making waste. If I place a clean up crew in my system I put food in for the fish in my system not extra because I have a clean up crew. They are there for left over, not extra.
Don’t know what I’d do without them! I have ~300 in my 115 gallon nps tank. I do NOT recommend that many in a normal reef system, lol. That tank gets about 3lbs of mysid, krill, Cyclopeeze and Rod’s, all mixed with Selcon, Zoe and.Fauna Marin foods, to boot. I have a very diverse cuc but the hermits remove the most, fastest, by far. I would have serious problems without them removing what my corals and fish miss
Unless you are feeding an organism directly, that organism cannot produce any waste that wasn’t already there. Yes they poop, but they are only further breaking down matter that was already in the tank.
I love crabs! A little drawn butter… Anyway, sometimes these posts don’t see the forest for the trees. If you like crabs, get crabs and don’t worry about the amount of fish you have. If your tank balance is off, worry about your maintenance regimen and stocking ratios on your fish, not how many crabs you have in the tank. I think that was the whole point. But then again, i may not be seeing the forest for the trees either.
sorry to continue one point like a dog worrying over a bone, but I’d like to try once more to define a ‘closed system’. a closed system is an isolated body of water. It has no natural system to replenish what is ‘used up’ by living organisms nor an avenue to be diluted or refreshed on a continual basis. As an example, I’m sure the dreamer hobbyist in many of us has fantasized about a giant aquarium with free water flow exchange from the ocean which is conveniently located just outside the house! ( no? Me? just me? my shrink is right then! LOLs). In that case the closed system would become an open system as the constant introduction of ‘new water’ would restore the minerals and remove the ammonia in the ‘alcove’ or aquarium. This all important intellectual characterization of closed system vs semi-open and open system is KEY to understanding the next concept of Ideal Base Readings in a closed system and determines the rate and amount of water changes to accomplish the return to I.B.R.
And in many cases, the modern O.C.D. hobbyist can be maintaining what we could envision as a semi-Open system. I wrote about this in a book I co-authored ( UK) on Ideal water parameters in freshwater pond systems.
Back to the subject– crabs, and other small inverts are of a small body mass but have active metabolisms. They certainly can’t produce meaningful ammonia compared to a full bodied active fish. But in a closed system, mass is mass. And metabolism of all types ‘take something out of water and add something to water in way of pollution.
It is try that ‘somethings’ leave the water via the surface * evaporation. Heat, carbon dioxide and many species of nitrogen gases and even some ammonia can be measured as it is released from water. Indeed the odor some hobbyists complain about is often gases escaping the system.
But this minor blow off does not change the realities of a closed system. In the end, returning to ALL base line measurements via dilution is the only true answer and identity of a closed system. Best, JasPR
JasPR I completely understand what your saying but in the grand scheme of what the topic is about I just don’t see how it’s relevant? The discussion is about the fact that hermit crabs, while they do produce waste not as much waste as fish. do you feed your hermit crabs?I don’t, do hermit crabs eat extra food on the sand bed and get into cracks and crevices fish don’t? I believe they do. if your tank is at full capacity and you find a fish you’ve always wanted on the cheap should you say ” I’ll just take out 10 hermit crabs and then I’ll be ok”?I don’t think the math would add up?
Most of us in this hobby have at the very least have a basic idea of a closed system and anyone that has a successful reef tank can say there way is the right way! but does that mean there isn’t other ways to accomplish the same goals? everyone can do research on the same subject and the same research material and come out of it with a different meaning.
Point is if you like hermit crabs and think they are great for your tank then get hermit crabs if not don’t. Just don’t think your 1′ long Angel fish is going to clean inside you live rock or dig down inside your sand bed to get some food. and without good husbandry it doesn’t matter if you have hermits or not!
by the way the outside 20,000 gallon tank with a direct feed from the ocean! sound awesome! you’d need an awfully big Uv sterilizer for that incoming water though! And hopefully it’s not a direct feed from the Hawaiian region as of lately! best regards from a guy that just likes to talk even if he’s wrong! sincerely Me
@JasonandSarah4
Well said. With any cleanup crew, their value rests in the fact that they remove more waste than they produce. Much like macro algae, waste is converted to energy which the animals use to live and grow. While they will produce some waste from what they take in, it is less than the amount they consumed, thus reducing the total amount in our systems
With an nps tank, I’ve become very good at monitoring and controlling pollution! That tank gets more food in one day than my larger reef tank does in a month! Although I keep a diverse cuc, consisting of various snail types; conchs, starfish, cucumbers and others; I’ve found hermits to be the best, fastest way to remove uneaten food, especially. They literally come running as soon as the food hits the water and search out any missed particles immediately. It took some time to get the right density (about 3 per gallon, for that tank) but, once I did, they became one of the most important parts of my waste removal. Without them, I would have to drastically reduce the number of non photosynthetic corals in that tank
I normally just read but my understanding is overstocked is
Overstocked you can’t take hermits out to get another fish
The bioload will still be to high . It would be like taken out a yellowtail
Damsel and putting in a tang or angel . Bioload going to double
Just my thought Pam
I really think the solution to all of this is don’t over stock? I personally under stock
and still go at least +1 on the skimmer and sump-turnover! if your under stocked and you want a fish no worrie just add it. or some hermits! 😀
Unless you have trained your hermit crabs to grab fish food or poop and physically throw it over the edge of the tank…then they do not remove anything from your system. The best they can do is to convert the excesses or waste you don’t want in your system in to a form which can be more easily removed via human intervention, i.e. through mechanical filtering, chemical filtration, skimming, trimming macro algae, water changes, a tiny bit from off gassing via circulation, etc.
The term “clean-up crew” is a bit misleading; more accurately they are a “conversion crew”. Clean-up (removal) remains up to humans.
Mark’s point in this tip is really very straightforward. The net waste a hermit crab leaves behind of things you don’t want in your tank is so small in comparison to a that of a fish that trading out virtually any number of crabs to reduce your overall bio load is pretty much pointless.
I agree in a way to what you have just started but I disagree as well. yes the words clean up crew can be misleading in a way but they do clean your tank in the form of reduction, they scurry around all day scavenging and climbing over and over again burning energy witch is converted from food and waste they eat. but they also produce waste and nothing is ever broken down 100% so that is where it can be misleading if you have diatoms, green algae, hair algae and so on and so in you cannot completely rod your self of this problem solely by getting yourself hermit crabs because some of what they eat comes back out same as it went in and if you have a small out break of some kind of algae I’ve heard hermit crabs and snails or even fish that eat it can spread it via they’re waste that contains some traces of what they are and is now spread across your tank. but with good husbandry and hermits and snails it’s very effective and if you employ all these things from day one you may never end up with these problems at all?
What must become apparent to even the most casual reader is the fact that I see all my systems as ‘closed’ or recirculating. This is key I think to having a good mental picture of what is really happening in that ‘glass box of water’.
Second to this idea is the old quote ” if you build it they will come”. In that vision/version of things, we accept that mother nature abhors a vacuum and she will fill any blank surface with something ( algae forms, bacterial forms, diatom forms, minerals and micro nutrient).
Key to tying these two concepts together will soon become sensitive to what nutrient is being added to the glass box that is not removed ( only converted) and secondly, how does that nutrient form favor or disfavor certain micro species as mother nature attempts to fill voids. Implied in this concept is the idea that every species looks to exploit conditions in the moment to insure survival of its species.
Ok, long winded, admittedly. But the point is this– “cleaning crews” that can be supported in very large numbers , by definition, means that too much nutrient is in the water column and it creates ‘food’ for the massive cleaning crew. In turn this crew is making a living and dumping nutrient back into the closed box. This has the potential of becoming a high wire act in that NOTHING can go wrong or a system can begin to crash- loss of power, change in lighting, reduced circulation, any oxygen demand will quickly effect the nitrification and CO2 and alkaline reserve system. This is ironically due to a very successful and complex ecosystem.
I’M NOT ANTI-CLEANING CREW! Honest! But do appreciate that a need for a massive cleaning crew is a statement about a progressive eutrification trend on a closed system. JasPR
agreed! I think a couple hermits per fish you have is sufficient. and I have a lightly stocked tank. this is just what I do in no way Is it a recommendation or guideline for anyone. like I said before if it ain’t broke don’t fix it! And if it is broke askl someone you know and trust that’s tank methods are working for them.
Side note I think we scared Mark away from his own web site on this one! Lol
He’s probably thinking” these people are crazy”!!! 😀