If there is one constant in nature, it's change.
And it's kind of ironic to me that one of the things we typically strive to avoid in fish keeping is change...well, rapid environmental change, anyways. Yet, we are always sort of modeling our aquariums after a variety of habitats, many of which do undergo significant periodic or seasonal changes during the course of a year, don't they? Yet we don't usually vary our conditions throughout the year in our aquariums...Almost sort of "static", right? I suppose it's another case of, "We do it this way because it's how we've done it for a century..."
Perhaps its time to loosen the chains of "conventional aquarium practice" and look towards some largely unexplored waters, right? Could there be something to be gained by modeling our aquariums after natural habitats during different times of the year? I think so!
Even the larger lakes undergo seasonal changes. For example, Lake Tanganyika, the second deepest lake in the world, undergoes surface water temperature changes throughout the year in its upper layers.
In Amazonia, floodplain lakes associated with the river also undergo seasonal changes, which affect water quality. At high water phase, the large amount of nutrient input from the terrestrial environment causes the increase of primary productivity, and can lead to the lakes becoming very "eutrophic."
And of course, we all know about the annual killifishes of Africa and South America, which have adapted over eons to the varying seasonal conditions of rainfall and desiccation, with slowly evaporating pools, puddles, and wetlands that may fill once again during the rainy season-whenever that may be- and are unreliable, yet dynamic environments, which give both life and death to the killies and other aquatic life forms which reside in them.
As hobbyists, I'd hazard a guess that we (unconsciously) tend to model our aquariums after one season in the wild habitats (if we even consider seasons at all), not really taking into account the significant changes that occur in these environments at various times of the year. If you look at it from a "literal" perspective, not taking into account the hobbyists who work with annual killies, for most of us, it's sort of "always the wet season" in our aquariums, right?
Now, there is certainly nothing wrong with this approach. After all, we're into keeping fishes, not creating dioramas of dry rainforest floors or empty mud holes! However, I think that it would be kind of cool to model our aquariums after typical environments at different times of the year. We've already touched on the flooded Igapo forests of Brazil, in which the forest floor becomes seasonally inundated by overflowing streams and rivers. It's an amazingly dynamic habitat that I'm glad we're starting to see more interest in. Yet, I wonder how interesting it would be to take it even further, and create an aquarium around the seasonal changes in such a habitat. You know, with more shallow water level, a greater ratio of botanicals/substrate to water, and different temperatures?
What about a vernal pool in Africa that houses annual killifish? Could different behaviors be affected by lowering the water level significantly at various times of the year, perhaps triggering behaviors related to the onset of the dry season? We already have a good handle on the spawning of fishes like Nothobranchius, and how CO2 and such affects egg viability and hatching, but I wonder if we could gain even more insight into the fishes themselves by gradually decreasing water levels to simulate this seasonal change? Or changing food sources to simulate the varying resources which are available during different seasons?
If you recall, not too long ago, we talked about the Zebra Danio, and how it adapts to changing conditions in its native habitats? Typically, these fishes are found in Northern India, and this area is subjected to seasonal rainfall between the months of June and September due to the summer Monsoon, and the water levels and characteristics vary considerably at different times of the year. They are often found in inundated rice paddies and marginal pools, with silty, kind of turbid water with very little movement. During the dry times of the year, they spend their time in calm, shaded areas of streams, with rocky substrates. How interesting it would be to give them "monsoonal" conditions, versus the conditions more typical of the dry season that we typically provide them in aquariums!
I find examining these seasonal changes in the natural habitats and how they affect our fishes irresistible! There is something very alluring about perhaps gaining some small insights into how the environmental changes that occur throughout the year affect our fishes. I mean, there's more to it than simply raising and lowering water levels or temperature. What kinds of secrets could you unlock about your fishes by manipulating factors such as turbidity, water movement, varying light intensity/duration, temperature (we've done this to some extent), pH, and even food supply? There is a lot of great scholarly data out there on almost any tropical environment you can think of, and with the concern over climate change, there is a lot of stuff analyzing seasonal variations in all sorts of aquatic habitats worldwide.
The passing of seasons and varying environmental conditions are fascinating opportunities for us as hobbyists to examine and learn about how our fishes interact with their environments, and how we might be able to create even more successful outcomes for a wider variety of fishes- perhaps even some which have typically eluded our intentional spawning efforts to date.
When we start working more with brackish habitats, we can examine the idea of tidal influences- more frequent changes to the habitats...something that has not been worked with very much in home aquariums in the past. What secrets could we unlock by playing with some of these ideas?
Now, sure, we already play around with some environmental conditions in order to induce spawning in our fishes, which is well-documented, so why not play around with (or at least examine) various types of seasonal conditions for fishes to see what other impacts we can influence (i.e.; greater growth rate, coloration, appetite, etc.)?
With all of the amazing curiosity, talent, and creativity in our growing global community of adventurous aquarists, I hope that I've piqued the interest of at least a few of you into taking a different sort of look at the way we plan, develop, and manage our aquariums. Not that taking such an approach will guarantee groundbreaking results, sure to change the way we keep our fishes (it might!)- but it might just stimulate more ideas, more discussions, and facilitate the "connecting-of-the-dots" process of weaving together what we already know with what we haven't yet tried.
It's an amazing time to be an aquarist, isn't it? I mean, we have the fishes, the technology, the materials, and the means to research arcane topics once considered solely the domain of scholars. And we can rapidly communicate and share our ideas, successes, challenges, failures, and overall progress with fellow hobbyists all over the planet.
Yeah, those "passing fancies" might just create some entirely new paradigms for our hobby. Let's hope!
Stay excited. Stay resourceful. Stay creative. Stay adventurous.
And Stay Wet.