Polyp extension in plumbed together tanks

[vcollins9850]

And absolutely beautiful tank

 

[cilyjr]

And absolutely beautiful tank

Thanks, it's getting there. It's 1 year old in March 2024

 

[cilyjr]

Here's a quick shot of the frag tank in question

 

[Cell]

Yeah, all that stock, I'd spend the money and rent or buy a par meter. I bet the difference between where the colony is in the DT and frag resides in the frag tank is significant.

 

[cilyjr]

Yeah, all that stock, I'd spend the money and rent or buy a par meter. I bet the difference between where the colony is in the DT and frag resides in the frag tank is significant.

Maybe. However, if that were the case, I would expect to see a difference between the upper and lower areas in the display.

 

[Cell]

Maybe. However, if that were the case, I would expect to see a difference between the upper and lower areas in the display.

Do you have duplicate frags/colonies growing in each area to compare?

 

[cilyjr]

Do you have duplicate frags/colonies growing in each area to compare?

Well sort of. There is a large digitia that's very high then a smaller almost at the sand bed both are about the same.

But regardless, there is little to no PE through the dt whether high or low. This is what leads me away from lighting...

Not saying it's not, but I would find it surprising.

Here's another piece of this puzzle, my Display is in the house while the frag tank is in a shed connected through plumbing. I've read gas exchange can be a culprit. So if there is less CO2 vs the display due to a more open environment maybe that could account for some of it?

 

[Troylee]

Well sort of. There is a large digitia that's very high then a smaller almost at the sand bed both are about the same.

But regardless, there is little to no PE through the dt whether high or low. This is what leads me away from lighting...

Not saying it's not, but I would find it surprising.

Here's another piece of this puzzle, my Display is in the house while the frag tank is in a shed connected through plumbing. I've read gas exchange can be a culprit. So if there is less CO2 vs the display due to a more open environment maybe that could account for some of it?

Doubt it.. that should just raise the ph of the system overall.. I’d say increased lighting and flow and like I said in post 3, angelfish which you did mention you have.. my coral
Beauty used to nip digis in my little cube but now it’s in a 300 with some really big tangs and it doesn’t mess with any sps it cruises through rocks all day.

 

[LobsterOfJustice]

It's 100% the angelfish. I say that as someone who has 3 angels in the display, so I'm no angel hater. But it's the angel. Even if you never see it pick. I'd be willing to bet you see great PE in the display tank after lights go out.

Think of it this way. Yes, you never see the angelfish pick. But thats because the polyps aren't out. You also probably never see the fish eating pods... but thats because all the pods are hiding. In a tank with no fish, the pods will be crawling all over the rocks and glass during the daytime. And in a tank with no pickers, the polyps will be out. Once the fish goes in, the "prey" becomes conditioned to hide so the mere presence of the predator is enough to keep the prey hiding.

 

[ScottB]

I should state I'm not really trying to change anything. Everything in the display tank is growing happily. I'm just curious as to what people think the culprit might be.

My personal theory is that I have a flame, angel and a few other fish that could be considered potentially predatory towards some corals.

You have your answer. Corals may be a little slow, but they are not stupid.

 

[cilyjr]

It's 100% the angelfish. I say that as someone who has 3 angels in the display, so I'm no angel hater. But it's the angel. Even if you never see it pick. I'd be willing to bet you see great PE in the display tank after lights go out.

Think of it this way. Yes, you never see the angelfish pick. But thats because the polyps aren't out. You also probably never see the fish eating pods... but thats because all the pods are hiding. In a tank with no fish, the pods will be crawling all over the rocks and glass during the daytime. And in a tank with no pickers, the polyps will be out. Once the fish goes in, the "prey" becomes conditioned to hide so the mere presence of the predator is enough to keep the prey hiding.

You have your answer. Corals may be a little slow, but they are not stupid.

Ok this has always been what I was learning towards.

Now how does this happen?
we are not talking about self aware animals.
Chemical secretion? What's your guess?

 

[cilyjr]

Yeah, all that stock, I'd spend the money and rent or buy a par meter. I bet the difference between where the colony is in the DT and frag resides in the frag tank is significant.

Here's another thing of interest that my wife pointed out that gives some more credence to the idea of it being related to lighting.
The frag tank being in a shed gets almost no natural light. There are no windows in that shed. The display tank is in a room where there is a large sliding door and several windows. The display tank does see a fair amount of natural sunlight.

 

[Troylee]

Here's another thing of interest that my wife pointed out that gives some more credence to the idea of it being related to lighting.
The frag tank being in a shed gets almost no natural light. There are no windows in that shed. The display tank is in a room where there is a large sliding door and several windows. The display tank does see a fair amount of natural sunlight.

From my experience I get better pe in sunlight.

 

[LobsterOfJustice]

Ok this has always been what I was learning towards.

Now how does this happen?
we are not talking about self aware animals.
Chemical secretion? What's your guess?

I've thought about this a little, and I wont claim that I have it all figured out. But the first thing to understand is that acropora do not extend their polyps during the day in the wild - because thats when the predators (angelfish, butterflyfish, etc) are awake. At night the fish sleep, and plankton moves up from the depths, so that is when they extend. So, we should be thinking of "lack of PE during the day" as the default state, not the learned behavior. In captivity, without threat of predation, the learned behavior is to extend polyps during the day. Same with my earlier example of cryptic microfauna - on the reef, pods, worms, etc woundn't dare come out from their hiding places during the day, but in a safe captive environment they can be conditioned to. I dont know the exact mechanism, but its probably not as complicated as it seems. I would guess there is even some ecological term for the phenomenon. But, it's essentially the same mechanism by which many wild animals are shy or even aggressive by nature, but over time certain individuals come to trust humans and there are examples of normally shy/aggressive wild animals tolerating close interactions with humans.

All that said, my guess is that the angelfish may pick at the coral extremely occasionally (like, only once or twice a month), or it could even be picking on nearby rocks, algae at the base of the coral, or food that gets caught in the corals tentacles or slime, but even this rare minor amount of picking is enough to signal to the coral that a potential predator is still present. Even if you watch your tank for several hours a day there is still a majority of the time spent without you watching, and I think it's also possible that the fish act differently when people are present (i.e. they focus on you as the source of food rather than scouring the rocks). So I think that there's a good chance that even the most observant hobbyist would miss an occasional pick or near-pick occuring one or two times a month, but that small amount is still enough to keep the polyps retracted during the day.

 

[cilyjr]

I've thought about this a little, and I wont claim that I have it all figured out. But the first thing to understand is that acropora do not extend their polyps during the day in the wild - because thats when the predators (angelfish, butterflyfish, etc) are awake. At night the fish sleep, and plankton moves up from the depths, so that is when they extend. So, we should be thinking of "lack of PE during the day" as the default state, not the learned behavior. In captivity, without threat of predation, the learned behavior is to extend polyps during the day. Same with my earlier example of cryptic microfauna - on the reef, pods, worms, etc woundn't dare come out from their hiding places during the day, but in a safe captive environment they can be conditioned to. I dont know the exact mechanism, but its probably not as complicated as it seems. I would guess there is even some ecological term for the phenomenon. But, it's essentially the same mechanism by which many wild animals are shy or even aggressive by nature, but over time certain individuals come to trust humans and there are examples of normally shy/aggressive wild animals tolerating close interactions with humans.

All that said, my guess is that the angelfish may pick at the coral extremely occasionally (like, only once or twice a month), or it could even be picking on nearby rocks, algae at the base of the coral, or food that gets caught in the corals tentacles or slime, but even this rare minor amount of picking is enough to signal to the coral that a potential predator is still present. Even if you watch your tank for several hours a day there is still a majority of the time spent without you watching, and I think it's also possible that the fish act differently when people are present (i.e. they focus on you as the source of food rather than scouring the rocks). So I think that there's a good chance that even the most observant hobbyist would miss an occasional pick or near-pick occuring one or two times a month, but that small amount is still enough to keep the polyps retracted during the day.

Thanks for this, What I like most is the idea that there is a lack of swimming Plankton moving around during the day. Possibly because of predation.

If Coral polyp extension is designed to catch this microfauna then the natural State would be to not have polyp extension if there is a lack of food. So, if your tank is extremely low in what they eat, then perhaps the lack of polyp extension is a symptom of that. Why spend the energy to extend if there's no benefit?

 

[Troylee]

Thanks for this, What I like most is the idea that there is a lack of swimming Plankton moving around during the day. Possibly because of predation.

If Coral polyp extension is designed to catch this microfauna then the natural State would be to not have polyp extension if there is a lack of food. So, if your tank is extremely low in what they eat, then perhaps the lack of polyp extension is a symptom of that. Why spend the energy to extend if there's no benefit?

To maybe reach for more light? Zoas and some LPs do just that… you can actually train your sticks to eat during the day believe it or not.. all these new bacteria concoctions that everyone is making including myself has proven just that.. after feeding gut loaded bacteria to your tank for a couple weeks you get some crazy feeding responses and way better pe during the day. I get a new frag it shows nothing for a couple weeks then catches on like the older guys in my tank it stretches and puts feeders out during the day like the rest. I have one colony in the swimming lane of my fish and it’s half open and closed all day cause the fish coming by spook it.. I’ll have to get a good picture of it.

 

[ScottB]

Ok this has always been what I was learning towards.

Now how does this happen?
we are not talking about self aware animals.
Chemical secretion? What's your guess?

Yeah I was kinda joking, but over millions of years these animals have evolved to protect themselves as best they can.

 

[Troylee]

Here’s one I was talking about.. it stays closed on the right side just cause of fish zooming by it all day while the rest reaches for the stars..

 

[Pod_01]

Observation I made on my tank, reefer 250 so nothing big. I have 3 led lights on it, 2 are Radion XR15 Blue and one Mitras 7206 and if I set the lights too high the polyp extension disappears on the sps, if I reduce it by 10/15% it returns.
SPS even stop growing.

Here is an example, elevated light:

Reduced by 15%:

Granted one tank etc… Done it few times same outcome.
Could be light related, not enough/too much.

 

[fersann]

Observation I made on my tank, reefer 250 so nothing big. I have 3 led lights on it, 2 are Radion XR15 Blue and one Mitras 7206 and if I set the lights too high the polyp extension disappears on the sps, if I reduce it by 10/15% it returns.
SPS even stop growing.

Here is an example, elevated light:

Reduced by 15%:

Granted one tank etc… Done it few times same outcome.
Could be light related, not enough/too much.

Your observation is gold!
Thanks for sharing