Growing Sargassum in a fish tank

Added: 2026-05-27

[00:00:01]So, last year while we were in Florida, I found some sargassum in the sea.

[00:00:09]And I brought some home and kept it over the winter and it stayed alive.

[00:00:14]So, um I'm going to try and farm it in this tank behind me.

[00:00:25]I managed to bring back with me about 10 or so gallons of sea water.

[00:00:30]I'm going to first fill it up with sea water and then fill it up the rest of the way with regular water and then add salt.

[00:00:38]Just to keep the appropriate salinity.

[00:01:20]This is about 8 gallons of water right here.

[00:01:22]So, it's probably a 20 gallon tank.

[00:01:25]So, I don't necessarily have enough salt for um 12 gallons of water.

[00:01:36]So, I may just put a few more gallons in.

[00:01:40]So, I'm going to fill these I'm probably going to fill it to about right this level.

[00:01:49]I'm guessing.

[00:01:51]So, I'm going to uh measure how many gallons I'm going to fill. I looked up how much salt is in seawater and it's a quarter to a third cup.

[00:02:06]So, I'm going to put about that much of salt per gallon that I put in.

[00:02:14]So, I'm going to put just regular canning and pickling salt.

[00:02:21]I'm going to put a cup in 4 gallons.

[00:02:39]This This uh This water came from the Gulf and the Gulf is usually is saltier than average.

[00:02:51]So, it's probably got more like a third of a cup per gallon. Most botanists put it in a protist kingdom instead of a plant instead of plantae.

[00:03:02]So, I think that's pretty cool. This sargassum is considered is called a brown macroalgae. So, it's and It's got It's very interesting the way it grows and everything.

[00:03:23]And the the parts of it have different names than regular plant parts cuz the leaves on it are not considered leaves.

[00:03:33]They're called blades.

[00:03:35]And the stem, I think, is called a thallus.

[00:03:41]I'll I'll give you a close-up view of it after I've dumped this in.

[00:03:59]>> There.

[00:04:00]That's 16 gallons of saline solution.

[00:04:05]So, it should be good. Ah, I forgot to strain it that time. Anyway, it's all good.

[00:04:15]So, this is what survived and what survived from my experiments this year.

[00:04:26]Um and it actually looks pretty healthy.

[00:04:30]It's growing very well. I can't wait to see what it looks like when I when it gets in good sun and enough water.

[00:05:01]It's like releasing a fish into the water.

[00:05:13]What I hope it will do and what it's supposed to do is make big mats in the Sargasso Sea.

[00:05:21]They That's why it was named the Sargasso Sea because of all the sargassum.

[00:05:29]There's lots of it.

[00:05:31]And it's a makes a good habitat for animals.

[00:05:36]So, I'll show you an up close of it.

[00:05:39]This is it in the tank.

[00:05:45]Those the those uh uh balls on it that look like at first I thought they were fruit or seeds or spores or something, but I did some research on it and I found out that they were actually air pockets.

[00:06:01]>> [snorts] >> And they're filled with oxygen.

[00:06:04]And they're they're called vesicles. And they help it float because if it sinks too far down, it can't photosynthesize properly. So, it keeps the leaves up close cuz it's a shallow water algae.

[00:06:17]There's also, if you look closely, there's these yellow they look sort of yellowish. It's hard to see them properly, but right here at the end, right there, those are actually reproductive bodies.

[00:06:52]And it's really interesting they it has its reproductive system is very complex and unique.

[00:07:02]It actually has um it it does a different uh different type of cell division for the rest of its reproductive system, not even not just the gametic cells.

[00:07:24]>> [clears throat] >> And uh so, it has basically haploid reproductive bodies, which means that each cell has half the number of chromosomes or half the sets number of sets of of the other regular cells, which is I which is strange in regular somatic cells.

[00:07:51]So, it's really interesting.

[00:07:55]It's the only type of organism that I know of that does that.

[00:08:01]I believe the species that I have is Sargassum fluitans.

[00:08:06]And I don't know if you can see it properly, but I think there is some new vegetative growth on there.

[00:08:18]But, um one thing that kind of disappointed me when I read about when I finally figured out that um my Sargassum was reproducing.

[00:08:38]One thing that disappointed me was that I found I read that Sargassum fluitans is almost always sterile. So, I don't know why it even bothers to put out reproductive bodies, but it will reproduce, hopefully very prolifically, vegetatively.

[00:08:59]So, that's very hopeful cuz it does form large mats in the ocean.

[00:09:07]So, I'm going to put in a comfrey leaf because they're high in nitrogen.

[00:09:14]And apparently, nitrogen really helps algae grow.

[00:09:19]And they don't burn in the same way that plants burn with nitrogen.

[00:09:24]So, there's actually a kind of a problem with algae blooms where there's more algae blooms in the sea now that there's been fertilizer dumping in the ocean. And the more fertilizers common and fertilizers being more commonly used.

[00:09:52]So there's been a lot more blooms lately.

[00:09:56]So that could be a bad thing, but also it could be seen as a good thing because means more biomass in the ocean.

[00:10:05]And more food for the fish to eat.

[00:10:07]And more carbon taken out of the atmosphere in the form of algae.

[00:10:14]But then it could also mean that there's more shade for the lower layers of the sea.

[00:10:20]And it might obstruct shipping, which what what whatever opinion you have of that will you'll think about it differently.

[00:10:32]But anyway that's that's it for this step.

[00:10:40]I want to I'm going to make a lid for this now or a shelter for this so it won't fill up with rain water and dilute the salt content.

[00:10:53]Okay, so this is the roof for it.

[00:10:57]I built a little cover so it wouldn't get wet.