- The coral that makes
our saltwater aquariums into reef tanks
gets most of its energy from the tiny dinoflagellates
that live throughout their tissue; most of it, not all.
And fish poop alone is likely not enough
to make up the rest of that.
So you should be feeding your corals.
But what's the best food?
It's hard to know,
and really there isn't much out there yet
on the science of actually feeding our corals.
We do know that Pocillopora, in particular,
will gladly accept newly-hatched brine shrimp
either with or without nutrient loading.
Hi, guys and girls, I'm ReefMan,
and today we're going to talking all about a paper
that is dedicated to feeding our corals.
And that paper is called
"The effects of feeding on the physiological performance
of the stony coral Pocillopora acuta".
There is a link down there in the description.
Please check it out if you're interested.
The paper, as always, has more information.
Now, if you were to go to a store like Marine Depot,
there's tons of options when it comes to coral food.
From dry powders like Reef Roids or NLS Reef Cell
to fish eggs and frozen rotifers
all the way to live phytoplankton.
We have all kinds of options.
The best option for you really comes down
to what kind of coral you keep in your tank.
Acropora, for example, it eats Rotifers,
but not so much brine shrimp.
Pocillopora eats brine shrimp, and more or less,
all of them will, to a lesser extent,
eat the freeze dried foods like Reef Roids
or similar products like the NLS.
It really comes down to the particle size
more than anything,
with Acropora preferring a smaller particle.
The trick, of course,
beyond just finding the right mix of live
and packaged foods that your coral will actually eat
is feeding your corals without impacting your water quality.
A small boost in nitrates alone might be fine,
but it does come with algae of all sorts,
and that's just gonna irritate and smother
the same corals that you're trying to feed.
In the paper, this was actually cleverly solved
by just using a different tank to feed the coral.
Simple enough, if all your corals
are mounted on frag plugs.
That's not realistic for most of us, though.
So be aware of your water parameters
when you're feeding your coral
and don't just start with handfuls of food every day.
Start it small, grow it gradually.
Now, stressed corals rely much more
on the food that they eat rather than on photosynthesis.
And actually a fully bleached coral is still alive
and it relies nearly entirely on food.
It's been shown by studies that feeding coral,
just feeding them, reduces the risk of bleaching.
In addition to raising coral protein levels,
it raises the concentration of chlorophyll
in the dinoflagellates in the tissue
and it even increases the rate at which those corals grow.
So, believe me, you should be feeding your corals,
even just once a week.
It's better than never.
Now, the team in the paper tested feeding coral
or not feeding coral and keeping it
at four different PAR levels: 105, 157, or 250 PAR.
And that's just a standard 12-hour on,
12-hour off light cycle.
Corals were removed from their tank each day,
placed in a feeding tank for four hours.
In that tank, they were fed two-day-old brine shrimp,
and then after that four-hour period,
they were returned to their original tanks.
In the best results, the highest light, that's 250 PAR,
with those daily feedings, the corals quadrupled in size
over the 140-day study period.
You can see that in the chart from the paper.
The gray blobs that you see there
and the gray line through them,
that indicates the buoyant weight of the coral frags
in each group.
They measured it by suspending it in water
and measuring the buoyant weight.
While the pink area on those charts
and the line that goes through the pink area
is the specific growth rate in percent each day.
You can see that the growth rate only increased
in the 250 PAR tanks.
In all of the other tanks,
the pink lines are actually trending negative.
Growth is slowing down over that period
or sometimes basically flat throughout the entire study.
Similarly, while all the corals did grow,
the rate at which the weight of the coral frags increased
is significantly better in the corals that received food.
And the fed coral all ended up larger
than the unfed coral frags did at the end of the study.
Now, having a tank full of big corals is really nice,
but having a tank full of big, colorful corals is better.
In the study, both light and being fed had a large impact
on the color of the coral.
The lowest light corals got darker
'cause they needed more photosynthesis,
and all the corals that were fed
got more colorful throughout the study
as compared to the unfed corals.
In fact, the unfed corals actually got less colorful
over the 140-day study period.
So, I hope it's pretty clear to you
that it is worthwhile to feed your corals.
I'll keep an eye out for research
into what corals eat what kinds of food the best,
so subscribe and you'll get a notification
when I find those answers.
For now, I like to feed
a variety of coral foods relatively often.
I turn off my sump and feed my corals
for a 30-minute period.
That gives the food time to flow around in my tank
before being removed my filter socks
or maybe my protein skimmer.
I would suggest that you do a similar thing in your tanks,
and you can just see what the result is.
You'll be able to see it with your own eyes.
I bet that your corals will thank you, they'll grow,
they'll be more colorful,
but do be careful about adding too much food.
Start small, less than you think,
and slowly increase the amount that you add
while watching your water parameters,
particularly your nitrate level
which should remain under about five parts per million.
So that's it for this video.
I hope that you found it interesting.
Stay safe, be kind to each other,
and I will see you next time.
Bye!