Now, I'm one of those aquarists who will be the first to admit that he really doesn't know squat about aquatic plants. I mean, I know who to identify a handful of 'em, and perhaps some of the basic nutrient needs of plants...but that's about it. I really like plants, but for some reason, they never quite "grabbed me" like fishes did. And, being really into blackwater aquariums, plants have always been viewed by me as a sort of a minor component, if that.
I think that, although aquatic plants are not a huge part of the blackwater biotopes that we are attempting to replicate, they do look pretty cool, and have some definite value (besides just aesthetics) that warrants their inclusion in our tanks. I see more and more hobbyists playing with live plants in blackwater botanical-style aquariums, and I think it's great! I hope to see more and more of this!
And there are some plants, like some fishes, which I have a very soft spot in my heart for, as this story will relate...
I grew up in a "fishy household." My dad was an avid breeder of fancy guppies (Blue Delta Tails, specifically).
And he, like me, was an avid reader of aquarium literature, and had an extensive library of fish books of the day. I spent many hours perusing them as soon as I was old enough to read! Most of these books were vintage 1960's, a sort of "golden age" for the aquarium hobby, when all sorts of interesting developments and advances were happening. Looking back, or even re-reading some of these now classic aquarium books reveals a lot of interesting "pearls of wisdom" which are often still applicable today.
I specifically loved reading about how breeders were setting up their aquariums for optimal functionality. This included information like tank size, filtration, husbandry, stocking...and the use of plants. One of the things I read over and over in my dad's guppy books was that most of the best breeders at the time felt strongly about the use of plants in their breeding tanks, specifically Water Sprite, Ceratopteris thalictroides. This plant was quite revered among guppy breeders. In fact, the common sentiment of the day was that, "If (your) Water Sprite grows well, so will the fish!" And even more general, "If you water is good enough for a healthy growth of Water Sprite, it will be perfect for guppies..."
There were even statements about how the top breeders of the day revered Water Sprite for it's "purification" properties...
I have wondered for years what it was about this plant which inspired such devotion among the guppy elite of the 1960's, and why this plant is still associated with them. With all of the attributes and strong statements made about this plant, there must be something special about them, right? Some kind of "magic" or something?
I suppose that it's not really that unusual a set of statements, when you think about it. I mean, if the water that you use in your aquariums supports healthy plant growth, it makes sense that it would be likely be acceptable to keep fish in. And of course, rapidly-growing plants do remove CO2, nitrate, and other organic nutrients from the water, right? In today's era of "high-tech/high concept" planted tanks, Water Sprite is equally loved as easy to grow, and reviled as a plant that can take over your tank if not tended to regularly. Now, is there some specific thing about Water Sprite that makes it extraordinary for guppies?
Well, it IS versatile. It can live in temperate and tropical water temps easily. It can grow immersed or emersed. It can grow rooted in soil, or floating freely in the water column. It can grow in both soft and hard water; alkaline and acidic...Hmmmm....could this beauty be one to use in a blackwater aquarium? I have kept it many times in relatively low-specific gravity brackish water (1.003-1.005) and it grew just fine, BTW...
Like most plants, it can remove nutrients from the water via its root system. It's fast growth and efficient nutrient uptake helps it outcompete many nuisance algae growths in the aquarium, which is always a plus in well-fed grow-out tanks. The plant's reproductive technique is similar to other ferns: small "adventitious plantlet" grow on the mother plant and are then released when they are ready to grow independently.
I suppose the big benefit of this plant for guppies is that it grows rapidly with minimal amounts of care, can provide protection, physical separation, and shade for young fishes. And, by virtue of it's fern-like morphology, it can retain bits of food for fishes to forage (a good and bad thing, depending upon how you look at it!).
I'm afraid that there is no real "magic" to Water Sprite other than the fact that it's all-around awesome. Oh, and the fact that you need not be a hardcore plant devotee to grow it well. And the fact that it's pretty adaptable. And can be grown in a number of ways. Oh, and it happens to look really nice. I think that its attachment to guppies is largely...well, sentimental in nature. It's continuously recommended for guppy tanks over virtually all other plants because it's sort of a "tradition" to do so. And, like many hobby traditions, this practice is really based more on an emotional attachment to this plant than for any specific reason.
Maybe THAT is the magic.
And quite frankly, there's nothing wrong with that.
Stay sentimental. Stay enthusiastic. Stay excited.
And Stay Wet.