Fuge or not?

I agree with this also +1

 

You are probably referring to amphiopods. LPS corals have sweeper tentacles for this purpose. Also Zooplankton is a primary component of most corals diet. This includes copepods, but these are tiny and not really visible to the human eye without a magnifying glass. Most corals have stinging cells to sting and catch pods, so, the don't need to "crawl" into the corals mouth.


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I could be wrong, with my current understanding of LPS feeding, I disagree.

My tank is mostly LPS and the only time I've seen a tentacle to mouth feeding move was after I placed food in it's tentacles. Amphipods stick to cover and don't just swim around getting snagged by sweepers. The fish that eat amphipods have to work hard to get at them. Unless small bits of food(copepods, phytoplankton, detritus) are absorbed by the tentacle itself, which requires no oral ingestion. May be the case?

For SPS I understand phytoplankton, small pods and fish poop make the majority of their diet. Because the tiny polyp can close when something small enters it. However, if you're running a skimmer or filter sock or both, then most suspended food in the water column will get removed. So, even for SPS, how much food is being actually supplied by the fuge?

The benefits of a sump/fuge are undeniable. Increased volume, bio-filtration, nutrient export, etc etc I totally agree! I'm just not convinced a fuge provides that much food that actually make inside of a coral.

 

Well, you are wrong, LPS corals do catch prey from various zones of the reef using their sweeper tentacles.

The fact that you've seen a "tentacle to mouth feeding move" indicates the purpose of these tentacles. There is no one around to feed corals in the wild, they need to catch their own prey. In fact the reason corals are able to out compete algae for space is that they rely on photosynthesis in the day and feed on various organisms at night.

I think one area of confusion is that you seem to be under the impression that pods are purely benthic organisms. This is incorrect. Many copepods and amphipods have benthic stages, but also can be demersal or pelagic and can have various stages at different periods of their life cycle, or even at different times of the day. In nature, most zooplankton migrate into the water column at night for example, from the benthic zone. Many corals will prey on them during this time.

However, corals are capable of consuming benthic organisms as well as pelagic. LPS corals can extend their sweeper tentacles several inches. Also, some soft corals have mechanisms shift and grab organisms passing by. Elegance corals are a good example, as they are easier to observe due to their powerful sting. Many people note a pile of snail shells around their elegance corals and occasionally people will even see the coral shoot it's tentacles towards a snail and grab it. They can do the same towards other smaller benthic organisms as well, as can most LPS corals, Although, most LPS corals do not have a powerful enough sting to kill a snail, so it can be more difficult to witness, with regards to these much smaller organisms.

Catching small crustacians, such as amphiopods as well as small shrimp, protazoa, bacteria etc... is the purpose of these tentacles, regardless of whether or not you have seen it. Benthic organisms do stumble into reach from time to time. This is well documented and there is absolutely no question about this. In nature this is not the primary source of food, however, purely pelagic food is fairly sparse in our systems, so, there is likely a larger proportion taken from the benthos and demersal populations.


See:
Reef Food by Eric Borneman - Reefkeeping.com
CorlFdgFAQ2

The sting of their tentacles paralyzes the prey and it can easily be pulled to the mouth. Remember this tends to happen at night so you may not see it. In a decade of reef keeping I have seen my corals feed, but not often. For one thing, once you shine a light in at night, everything hides. More often I have seen carcasses being expelled when a coral "poops" though, so I know it is happening more often than I witness.

Many people believe corals eat phytoplankton, however, research shows that corals do not likely digest phytoplankton. Eric discusses this here: The Food of Reefs, Part 3: Phytoplankton by Eric Borneman - Reefkeeping.com

There is more evidence to support this now, although I am not aware of a more recent non-scientific review.

The primary coral food source in nature is bacteria:
The Food of Reefs, Part 5: Bacteria by Eric Borneman - Reefkeeping.com

That is tough to answer. The pods can hide in the fuge during the day and swim into the water column at night. This provides a safe zone for reproduction. So, a fair amount may be supplied as they enter the water column at various stages. The skimmer will remove some, but it's questionable to me how efficiently a skimmer would remove a pod. Skimmers are better at removing amphiphilic proteins and likely to a smaller extent small single cellular organisms such as microalgae and bacteria. Phytoplankton for example is rare because it is removed faster than it reproduces, zooplankton is likely sparse for this reason, however, many believe that providing a safe zone in the fuge will help maintain some population, so knowing that food is sparse, this could be quite important. Certainly no one knows for sure though.

It is tough to say how much makes it to corals. There is a difference between nature and our systems. In nature zooplankton is a component of the coral food chain. In our systems, that component is very sparse, however so are other sources. Having an area to shelter it from predation is likely important. It still may be sparse, but sparse may be better than none...

 

Well I guess that leads to a new experiment I was gonna run 1 with halide and 1 with LED so after thats done Guess ill try 1 fuge and 1 not. they are both 30 gal breeder tanks so to do 1 fuge and 1 not would be hard to notice any true difference, since im using 1 halide and 1 led. I think the lighting test would detract from the noticable difference of fuge or no fuge. But for now I think ill use a fuge on both until I finish the lighting experiment

 

"It is tough to say how much makes it to corals. There is a difference between nature and our systems. In nature zooplankton is a component of the coral food chain. In our systems, that component is very sparse, however so are other sources. Having an area to shelter it from predation is likely important. It still may be sparse, but sparse may be better than none..."


Pretty much what I was getting at.

 

The key point is no coral can thrive 100% on light alone. They need food. If there is any easy way to provide live food, that will not decay and pollute the tank, that is likely better than dead food that will. We know something about food chains in nature, but less about them in captivity. You sort of need to use your best educated guess as to what food sources will be most beneficial and productive. Foods such as pods and bacteria are easier to propagate and less likely to be filtered out than other sources. Therefore these are the sources I primarily try to encourage. That is my best educated guess...


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