September 22, 2018

Morning Botanical Dossier: Clear water, diversity, and tragedy...the allure and lessons of the Rio Xingu.

As much as we love the reply titled blackwater habitats of Asia, Amazonia, Africa, and elsewhere, there are many, many more aquatic habitats which feature a variety of botanical and other materials and create lots of opportunities for us to create amazing aquariums!

Many of the fishes we love so much come from so-called 'clear water" habitats; that is, ecosystems in which the water is not darkly-stained by dissolved tannins and tunic substances. Rivers like the Tapajos and the the subject of today's microblog, the Rio Xingu, which originate to the north and southeast of the Amazon lowlands, where little erosion occurs, carry a small amount of sediments and undissolved materials.

These waters are lightly acidic, making the replication of their characteristics for aquariums rather easy and accessible for many hobbyists who are perhaps not as enamored of the highly acidic, deeply tinted blackwaters we talk about so much here! Adding to the allure is the fact that the Xingu has many interesting and popular fish species which we are already playing with, and it makes attempting to replicate this habitat far more interesting!

The Xingu is actually slightly "greenish" in color, largely from resident phytoplankton blooms, and has a ph ranging from 4.5-7.8...that's quite a wide range, huh? During the flood season of November to April, the water depth in the Xingu can fluctuate up to 5 meters! The water levels usually hit their peak between March and April, and the river often has an almost "lake-like" appearance because of it's width and lack of significant sedimentation. The Xingu is not particularly "nutrient rich", except maybe near its headwaters, where a significant diversity of aquatic vegetation and other life forms are found. It accounts for almost 5% of the water in the Amazon region.

So, yeah, if you're into plants, like some botanicals, and have an interest in fishes from this region...this could be a cool area to replicate, huh?

When I last researched it, the fish fauna of the Xingu is around 140-odd species, with around 50% being characoids (Yay!), and the remaining significant percentage being comprised of cichlids and Loricariids.

The Xingu has been under siege, so to speak, from mankind for over 40 years, with the much-hated Belo Monte Dam, which has caused significant ecological damage to the region, much to the chagrin of scientists, ecologists, the residents of the region, and just about everyone else who shares a love for the aquatic environment.

Although we're not going to discuss this issue in this piece, as plenty is written elsewhere, I'd be remiss if I didn't bring this up as a challenge to the existence of this priceless ecosystem. All aquarists with more than a passing interest in the environments from where their fishes come from should familiarize themselves with this story. It's a true disaster of epic proportions, and should serve as a model for generations to come of how mankind's greed and short-sidedness can result in disastrous consequences for the environment.

(Hypancistrus zebra- Image by Birger A Used under CC BY-SA 3.0)

Without simply shrugging this off, we can certainly learn more about what this habitat was like before man interfered with its very existence, and perhaps contemplate replicating some of the less-affected locales in the Xingu...perhaps as an homage to what was.

Unlike the soil and leaf-litter-dominated underwater topography of many Amazonian systems, the Xingu is, in most areas, covered with a wide assortment of rocks of various sizes over its soft, claylike substrate. What implications for the biotope-loving aquarist are there in this habitat?

The rocky areas are home to a wide variety of fishes, such as the much-loved Plecos, as well as numerous characins, Apisotgramma, and other species of catfishes!

Today's quick hit is really based more on a number of questions I've received from hobbyists asking about what botanical materials that I'd recommend using in an aquarium representing fishes from this region. Now, obviously there are many materials to choose from.

Personally, I'd stick with some of the "staples"- leaves; specifically, more "durable" ones, like Jackfruit, Artocarpus, and perhaps Mangrove. Now, all of these will provide some "tint", but not to the extent of say, Catappa or even guava.

And on the botanical material side, I'm inclined to recommend stuff like Fishtail Palm Stems, "Lampada Pods", Coconut Palm Stems; stuff that doesn't impart too much tint into the water.

More than anything else, I'd take some time to really look at the specific region of the Xingu I was interested in replicating before you get going. There is a ton of information out there!

This is a very quick, very broad "dossier," just to get you started, on some interesting facts about this unique river- a river which needs attention not only for its fascinating diversity, but for its vulnerability and the danger it faces from man. The unique and varied habitats of this river are well worthy of replication in our aquaria! Do some research on this river- you'll find tons of research out there.

Let's learn more about and replicate the habitats of this beautiful river- before it's too late.

Stay curious. Stay creative. Stay engaged. Stay excited...

And Stay Wet.

Scott Fellman

Tannin Aquatics