Fishkeeping and Thoughts of D&D

So over the past few months I got sucked into the rabbithole that is known as planted tanks (or planted aquariums) via YouTube and I took the plunge recently to start two small tanks of my own. As I've been working on them, a few things have struck me as being potentially relevant to gaming so I wanted to share some of what I learned here.

Introduction to Fishkeeping Concepts

One of the neat things about folks who are specifically into planted tanks is that they often are attempting to be world builders. That's because many of them are doing planted tanks as a way to reproduce a bunch of a natural cycle (sometimes in an effort to reduce the upkeep of an aquarium but often because they are super interested in the art and science of it).

To help understand, keeping an aquarium functioning is all about the nitrogen cycle. Animals get fed, they produce waste (ammonia), and ammonia is pretty toxic to the animals. Aquariums typically rely on two different types of bacteria to convert the ammonia to nitrites (which are also toxic) and then nitrites to nitrates (which are less toxic). Water changes often are a way of removing the nitrates from the system, but plants can also remove some of these from the water in addition to providing much needed oxygen for the fish.

In addition to this chemical balance, many attempt to create eye catching displays and sometimes even tell a story through their aquascapes. This in particular made me think of roleplaying games. First is the creation of zones in terms of the water column, usually dividing the vertical area of the tank into thirds. Some fish and other creatures are considered denizens of the bottom, some prefer the middle layer, and others like life at the top.

For plants, we often think in terms of carpeting (plants that cover the substrate like a carpet), foreground (typically shorter or slower growing plants that would be at the front of the tank), mid-ground (plants for the middle of the tank), background (taller and/or fast growing plants), and floating plants (plants that float in the water, especially at the top of the tank). Each of these have their uses and help tell the "story" of the tank.

Another interesting concept is that of the community tank. These are tanks where the species chosen are meant to work well together. So you might have some inhabitants who are meant to be cleaners (shrimp, snails, some types of catfish, etc) and where they might help keep the populations in check since some tank inhabitants can become prolific breeders in the right conditions. This reminds me of quite a few D&D modules including the Caves of Chaos.

Using in an Adventure

There can be a number of reasons why someone or something might be keeping an aquarium in D&D. A wizard or apothecary might find them to be incredibly useful for keeping creatures that produce vital components to spells or potions. A druid might work on creating one to save local creatures during a time of intense climate change. A noble might wish to display their wealth and worldliness by displaying creatures from far away lands.
People have kept fish for thousands of years in outdoor pools or indoors in ceramic vessels not to mention in ponds and the like. For something truly fantastical, imagine the existence of a force field that creates a large area of glass for displaying aquatic life. Perhaps a wizard created one in an underground cavern and stocked it with phosphorescent plants and creatures from the ocean deep.

Or perhaps long ago, a vibrant and verdant land began to turn to desert and thus an effort was made to save the local creatures, moving them into a cavern filled with sunstones that mimicked the passage of the sun. The keepers have all died but their world continues to live on.

What creatures would you stock these aquariums with? How would you tend to the needs of all of the livestock? How would you keep balance? How would the introduction of player characters affect this balance?