With all of the "crossover" occurring now in the specialty aquarium segment of the hobby, we're seeing an uptick in interest about mixing plants with blackwater environments. There are a lot of questions on this sort of mix; specifically, what plants can you keep and which are the most adaptable.
Now, I'll start right off by telling you that plants are not my area of expertise. Most of you have forgotten more about them than I'll ever know! I've touched on them once before in this blog, however. That being said, I do have some small experience keeping plants in blackwater aquariums, and have formed some opinions on them. My hope is that this post will at least form the basis for a discussion, with participation and input from those of you who have more extensive knowledge and experience with aquatic plants, and possibly, aquatic plants in blackwater systems.
First off, there are a surprisingly large number of plants that actually occur in blackwater-type habitats in the wild. I think some of the more compelling examples that we can keep in aquariums are found in Asia, in places like Malaysia, Borneo, etc., and include a healthy number of species sort of familiar to aquarists, so lets touch on them today.
The most immediately recognizable are species of Cryptocorynes are the first type of plants that scream "We live in blackwater!" to me. (really!) They are adapted to extremely acidic environments- sometimes as low as pH 3.5! Now, just because they can live in such extremes doesn't mean they have to. Low to non-existent carbonate hardness (hey, RO/DI water!) is good! If your pH finds itself in the "high fives" and "low sixes", I think you'll be fine. And the interesting thing about blackwater Crypts, is that they don't need a lot of nutrients - actually they are adapted to get along with very, very little in the way of nutrients! In culture, they certainly benefit from having more nutrients available than in nature, but you don't need to go crazy with fertilizer. So, those of you that feel that you need to be dosing all sorts of stuff and wonder about the impact of that in a botanical/blackwater system...don't have to!
Besides, some cool, well-fed fishes, like wild Bettas, will help provide some of the nutrients the plants need...for free!
And one more thing: With blackwater Cryptocorynes, it's important to think of the soil they grow in as an ecosystem of its own. This means that you probably would want to create a nice, rich substrate and not mess with it. I mean, every time you adjust some specific factor in fertilizing plants- especially touchy ones like some Crypts- there could be all sorts of possible negative effects...Don't overdo it. Just give 'em a rich, balanced substrate and concentrate on the other aspects of the aquarium. A bunch of blackwater/Crypt fans I know are big into letting their leaves decompose completely into the substrate in their tanks, serving as an "in situ" source of compost! This is "right up our alley", huh? And yeah, some grow emersed, too.
And back to the whole pH thing again...although many of the blackwater Crypts can grow in higher, even neutral pH, take into account the fact that they do better at lower pH levels. And as for lighting, they categorically don't need a ton of light, so well-tuned LED or other lighting methodologies would suit these plants just fine!
I think those of you that love Asian biotopes would do well to go for some Crypts. Sure, there are some pretty obscure ones, like Cryptocoryne yujii, and Cryptocoryne pallidinervia but you can definitely do well with Cryptocoryne cordata, Cryptocoryne ciliata, C. longicauda, C. pallidinerva, and even C. grifithii, which are not uncommon at all in blackwater habitats. And you could also add various specimens of Barclaya to round it out a bit.
( B. motley -Copyright, Patrick Blanc)
So why stop with just using the plants? I mean, there are some very cool species of fishes, some of which enthusiasts know already- which deserve our attention that come from these blackwater peat swamp environments: Wild Bettas, like Betta brownorum, Betta akarensis, and Betta coccina are found in these types of habitats. Other cool fishes, like the increasingly popular Sundadanio axelrodi, and the more exotic "Bumblebee Catfish", Nanobagrus fuscus also may be common in these locales.
With a little research, one could replicate the combinations of fishes and plants common to these environments, and create a nice little biotope aquarium in the process!
Aquascaping tip: Include some palm fronds, as many of these habitats have palm trees overhanging the water, with fronds often falling in.
Okay, I could probably go on and on and on, but I think just firing off the opening salvo in a discussion which I hope those more learned than I will jump into is good enough for now!
Let's hear from those of you who keep plants in your blackwater tanks. Specifically let's talk about your selection, substrate, fertilizing regimens (if any), and lighting.
Stay involved. Stay creative. Stay adventurous.
And Stay Wet!