polyps not extending on SPS... Is it fish?

[McPuff]

Reefers, I'm trying to figure out why my SPS (many, but not all) will not fully extend their polyps. All of my species are either large frags or small colonies at this point FYI. There is no pattern to which corals are opening and which are not. Some acros are mostly open (green slimer, blue staghorn, chalice, blue milli), some are half open (bird of paradise, pink birds nest, yellow table) and some are fairly closed (pink table, scroll, blue digi). These are just examples, there are more.

More info... My parameters are all in the proper ranges.

Ca - 440
Alk - 8.6 dKh
Mg - 1390
temp - 80 daytime
PO4 - 0.03
NO3 - low but don't remember number
even K+ is up where it needs to be.

Lighting - 3 x 175MH (20,000K) (2 @ 8hr, 1 @ 5 hr) and 80W actinics (10 hr)

Flow could be higher but is good... lots of movement and no dead spots anymore... also adding SCWD to return soon to make flow more variable.

The fish: blue face angel, flame angel, barred rabbit, pink spotted hawk, watchman goby, royal gramma, blue throat trigger (wow, I need more fish!). All are reef safe except for the two angels ("use caution"). Still, I do not SEE the fish pick at any of the corals any time I am watching them. I am prone to say it's not the fish.

Coral feeding: For the longest time, they were fed light, nothing else. About two months ago I started to feed the corals (oyster feast) about every other day. The past few weeks I cut it back to ~ once a week (because of all the changes in the tank - rearrangement). Now I will ramp back up to every other day. It does seem to help polyp extension right away but not in a huge way.

Fish feeding: I feed the fish ONCE per day and they get pellets... has been this way for years. Every few days I also give them caulerpa. I just bought an automatic fish feeder so I will start to feed them 3-4 times per day because I know it's good for them to eat more often. I don't feed frozen much at all anymore. Maybe I should more often?

Question: Has anyone else found that by feeding the fish more often, the corals look better? If the fish were picking at the corals, the polyps would largely remain withdrawn. But as I said, I haven't seen them pick. However, when I am watching my fish, I have likely just fed them so they are happy. It is possible that my fish pick at the corals during the day because they are hungry.

I've seen pics of incredible corals that are not fed anything but light (yes, fed light). So what is going on here? Is it the fish? Is it something else that I am missing? Is it actually quite important to feed the corals? Will continued coral feedings bring out more color and polyp extension? Do you recommend another food type for the corals? I welcome your suggestions and I am eager to read about your thoughts. Thanks!

[mike_cmu04]

175 metal halides may not be enough light for sps further down in the tank are the ones with the polyps not extending further down? The angels could be nipping and probably are. Feeding the corals likely is not the issue they will be fine not being fed at all just feeding off fish waste is enough. If your flow isnt strong enought that will definently cause it too what are you using for flow'

[CUNAReefer]

Hi Damon,

Hope all is well!

It could very well be your fish. I had a filefish (recently went carpet surfing) that was nipping at some of my corals. I did not catch him early on, but once he really started nipping at the corals... he started eating patches of coral in front of me. He was my favorite fish and I was having trouble with the decision to give him away. Even though he was nipping the coral, I really wanted to find him a good home. One morning I came down to the basement and found him next to the tank as dry as a potato chip. I was sad but the couple of corals he nipped returned to normal.

Also, elevated levels of nitrate can cause the polyps to retract. There shouldn't be any issues with your cutting back feeding the coral. There are some very successful tanks that do not feed the corals any food, but rely on light, the established meiofauna, and fish waste. ULNS do require additions of food. Due to the lowered level of Zooxanthallae, the food produce through the utilization of light is lowered. Less Zooxanthalle equal brighter colors. Some of the other tanks that do not feed at all have large populations of fish or other foods sources (i.e. refugium, algae scrubber, etc.). If you want to experiment with another type of food, check out Zeovit's Coral Vitalizer. Great stuff!

Warmest Regards,
James

Originally Posted by McPuff

Reefers, I'm trying to figure out why my SPS (many, but not all) will not fully extend their polyps. All of my species are either large frags or small colonies at this point FYI. There is no pattern to which corals are opening and which are not. Some acros are mostly open (green slimer, blue staghorn, chalice, blue milli), some are half open (bird of paradise, pink birds nest, yellow table) and some are fairly closed (pink table, scroll, blue digi). These are just examples, there are more.

More info... My parameters are all in the proper ranges.

Ca - 440
Alk - 8.6 dKh
Mg - 1390
temp - 80 daytime
PO4 - 0.03
NO3 - low but don't remember number
even K+ is up where it needs to be.

Lighting - 3 x 175MH (20,000K) (2 @ 8hr, 1 @ 5 hr) and 80W actinics (10 hr)

Flow could be higher but is good... lots of movement and no dead spots anymore... also adding SCWD to return soon to make flow more variable.

The fish: blue face angel, flame angel, barred rabbit, pink spotted hawk, watchman goby, royal gramma, blue throat trigger (wow, I need more fish!). All are reef safe except for the two angels ("use caution"). Still, I do not SEE the fish pick at any of the corals any time I am watching them. I am prone to say it's not the fish.

Coral feeding: For the longest time, they were fed light, nothing else. About two months ago I started to feed the corals (oyster feast) about every other day. The past few weeks I cut it back to ~ once a week (because of all the changes in the tank - rearrangement). Now I will ramp back up to every other day. It does seem to help polyp extension right away but not in a huge way.

Fish feeding: I feed the fish ONCE per day and they get pellets... has been this way for years. Every few days I also give them caulerpa. I just bought an automatic fish feeder so I will start to feed them 3-4 times per day because I know it's good for them to eat more often. I don't feed frozen much at all anymore. Maybe I should more often?

Question: Has anyone else found that by feeding the fish more often, the corals look better? If the fish were picking at the corals, the polyps would largely remain withdrawn. But as I said, I haven't seen them pick. However, when I am watching my fish, I have likely just fed them so they are happy. It is possible that my fish pick at the corals during the day because they are hungry.

I've seen pics of incredible corals that are not fed anything but light (yes, fed light). So what is going on here? Is it the fish? Is it something else that I am missing? Is it actually quite important to feed the corals? Will continued coral feedings bring out more color and polyp extension? Do you recommend another food type for the corals? I welcome your suggestions and I am eager to read about your thoughts. Thanks!

[NewBostonConst]

i think it is the fish....I have a flame that died and the next day all the coral were extended. I never once saw him touching a coral.

[10K]

Damon,
It may very likely be the fish (my Flame is very sneaky), but it can obviously be any number of things. I know that pink table very well and it should extend and look very fuzzy. I am sure you took this into consideration, but make sure it is getting PLENTY of light and very good indirect flow. Just as a side note, I do not supplement with coral food. This may be an unusual hypothesis, but is there a chance they are not extending as much because they are getting more of their basic needs met with additional feeding? Could they be less dependent upon the light, hence the lack of extension for more exposure? Is the growth still good or do they seem stunted? The table shows very obvious growth tips when conditions are satisfactory. Keep in mind the table is reasonably new to your tank, so you may want to think of this with your longer standing residents. Was there any change when you started to feed?
You mentioned 80 degrees during the day. What about at night? What is the swing? 80 is not a big deal, but if you are seeing 3-4 degree changes every 12-18 hours, then I have to imagine it is creating some additional stress.
Just some ideas…….Good luck!!

[gablett]

Most likely a combination of fish and not enough light. I 180 really needs 250s. I run my 250s 9 hours a day in a 220 which is only a little deeper than your tank.

[McPuff]

Thanks for all the replies thus far! Let's see... all of the branching corals are as high up as they can go and they are all in some decent flow. I will have to check the nitrate again to make sure it's not too high (like I said the PO4 is good). I will hold off on the coral feeding for a while and see what happens. I have started the increased fish feedings now so perhaps that will help too. I was also planning to start the vodka dosing to try and get to ultra low nutrient levels and that, in theory, should help with polyp extension. Dave, the pink table is high up in the tank but is also toward the back. Maybe I will move it toward the middle more and see if that helps. The flow is pretty strong where it is located... and indirect. Again, the yellow table is extended much more so it could still be adjusting. The blue stag right next to it has begun to open up much more in the past week. The green slimer is to the other side and is also quite open. I agree that the lighting is a bit low and I am definitely planning to increase the PAR. I will soon place an LED strip with 14 diodes along the front so that should help anyway. I also hope to improve flow sometime soon with larger pumps. Currently I have two opposing koralia 1400s and a Seio pointed toward the back. The water moves well but I know it could be better (and probably needs to be).

To recap, the following changes will be implemented soon:

-increase PAR with LED strip (42W) (replacing PC actinic 2 x 40W)

-addition of SCWD to return line to improve flow variability

-vodka dosing to strive toward ultra low nutrient levels

AND, just recently I did a fairly large rearrangement of my rock work. Last night I was noticing that some of the corals were coloring up more and I assume it's because the tank is nestling back into that stable zone as it were (though the levels were all fine throughout).

I'll have to impose each of the above changes one at a time so I can determine the relative influence of each and report back on it. Thanks again for your comments and ideas! They are much appreciated.

[McPuff]

Update: Started the 3x daily fish feeding a couple days ago. Coincidentally (or not), some of the corals have begun to extend their polyps further. For a couple corals, it's the best extension I've seen since they've been in my care. Another change is that I scraped the algae off the back panel... just about all of it (coralline included). I let filter socks and padding collect the waste for a day and now the tank is about as clear and bright as ever. Tested nitrate and it's at 0 so nutrients are in check. Finally, all pumps are recently super clean and have likely improved the flow a touch. So it seems things are shaping up nicely. Still have to make the aforementioned changes and those should lead to even better conditions.

Hopefully the trend continues... I'll report back in a week or so.

[mf2055]

sounds like things are getting back on track, good luck keeping it trending that way.