That Name Again is Mister Doug

"Meester Doug, that's my name. That name again is Meester Doug."

Every time I walk up to the tank and can't immediately find Doug, I sing this little jingle. Not because it serves a purpose. Not because I expected anything to happen. Mostly because I find it amusing.

At some point, however, something changed.

Now, if I walk up and start asking where Meester Doug is, he usually appears.

Does this mean Doug recognizes his name?

Probably not.

What is far more likely is that Doug learned something much simpler. The giant standing outside the glass making weird noises is usually followed by food, attention, or something interesting happening. This makes the weird noise important.

This is something I think fishkeepers often underestimate. Fish are remarkably good at learning patterns.

The filter turns off? Food is probably coming.

The lid opens? Maybe food.

A shadow appears at the front glass? Better investigate.

The person with the turkey baster shows up? Definitely investigate.

Fish spend their entire lives learning patterns because patterns keep them alive. In nature, patterns tell fish where food appears, where predators hunt, where shelter exists, when tides change, and when conditions become dangerous. The aquarium does not remove this behavior. Instead, we accidentally become part of it.

This is why fish often appear far more intelligent after keeping them for a long time. The fish did not suddenly become smarter. You simply spent enough time together that both of you learned each other's routines.

So no, I do not think Doug recognizes his name.

I do think that somewhere inside his little fish brain, however, he has concluded that hearing "Meester Doug" means something important is probably about to happen.

And honestly, I think that's pretty cool.

The Lonely Fish

One of the stranger things that happens when keeping fish is that over time, fish stop looking like fish.

That sounds odd to say, but the longer someone spends around aquariums, the less they tend to think in terms of species and the more they think in terms of behavior. A corydora stops being “a bottom feeder.” A tetra stops being “a schooling fish.” Instead, patterns start emerging. You learn what comfortable looks like.

A comfortable cory doesn’t sit still for long. It wanders. It roots through the substrate. It follows other corys for reasons known only to corys. They rest together, forage together and occasionally make synchronized trips to the surface as though they collectively forgot they were underwater. Tetras move with purpose. They join each other. They respond to each other. They become part of the movement of the tank rather than existing separately inside it.

That change in perspective creates an odd problem.

You stop noticing only when fish are sick.

You start noticing when fish stop acting like themselves.

One of the saddest things to watch becomes a social fish with nothing social around it. Not because fish necessarily experience loneliness in the same way humans do. That’s difficult to measure and easy to project onto. Instead, the discomfort comes from watching behavior disappear.

A lone cory doesn’t always look unhealthy. Water can be perfect. Food can be available. There may be no obvious signs of disease. Yet sometimes they stop wandering. They sit in corners. They stop exploring. A tetra alone may hover in place rather than moving through open water. Nothing appears wrong until you compare it to what those fish look like when surrounded by others.

That comparison changes how people think about care.

Early in the hobby, success often means survival. Then it becomes health. Eventually, for many aquarists, it becomes something harder to define: does this fish get to behave like the animal it evolved to be?

That question changes things.

A school stops feeling decorative. Groups stop feeling optional. Extra fish stop feeling redundant. Suddenly adding another cory isn’t adding another fish. It becomes restoring a behavior.

The strange thing is that once someone learns to see fish that way, it becomes difficult to unsee.

A lone fish starts to stand out.

Not because it is dying.

But because you’ve seen what that same fish looks like when it’s comfortable.

And once you’ve seen fish act like fish, it becomes difficult to settle for less.

When Knowledge Becomes Noise

One of the greatest things about the fishkeeping hobby is how far it has come in understanding ecosystems, biology and ecology. For those who enjoy diving deep into the mechanics of an aquarium, that knowledge can be incredibly rewarding.

The problem is that most people who want a simple betta tank are not looking for a crash course in aquatic microbiology. They are not trying to memorize nitrogen compounds or understand bacterial colonies. They simply want to keep a fish healthy and happy.

Somewhere along the way, fishkeeping became a hobby that often teaches beginners like they are preparing for a biology exam. Before they have even learned basic maintenance habits, they are introduced to ammonia, nitrite, nitrate, pH, KH, GH and endless online debates about the “correct” way to run a tank.

Meanwhile, the foundations of successful fishkeeping are usually much simpler.

Do not overcrowd the tank. Feed lightly. Perform regular water changes. Give the aquarium time to mature. Observe the animals. Leave stable systems alone.

This is not to say that the nitrogen cycle is unimportant. It absolutely is. The issue is assuming that understanding the science is the same thing as understanding fishkeeping.

A beginner does not necessarily need to understand every bacterial process happening inside a filter. What they need to understand is that filters take time to establish, fish produce waste constantly and maintenance is normal.

You do not need to understand combustion chemistry to know that a car needs oil changes. In the same way, you do not need a degree in aquatic biology to understand that an aquarium requires patience and consistent care.

Sometimes, information helps people understand a system better. Other times, it overwhelms them before they have learned the practical habits that actually keep the system healthy.

Knowledge is valuable. The problem begins when knowledge becomes noise.

Not If, But When

I recently had a long weekend out of town. Since I was only gone from Saturday to Tuesday, I figured the fish would be fine without someone watching them. I know my equipment. I know my ecosystems.

The good news? Everyone was fine.

The bad news? The return pump on the reef threw an error code and stayed off for most of the trip. This meant less flow, less oxygenation, and no heated water returning from the sump.

So why was everyone okay?

The answer comes down to redundancy.

The reef had enough live rock in the display to handle the biological filtration without relying heavily on the sump. The rock in the sump is honestly more for structure and habitat for the sump inhabitants than critical filtration. More importantly, though, the tank still had circulation. My gyre kept water moving, oxygen exchanging, and the reef alive.

Technically, I do not need both a return pump and a gyre. Plenty of systems run one or the other. But I tend to be a bit paranoid when it comes to life support systems. This time, that paranoia paid off.

Growing up around electronics and understanding them more than most people my age, I learned something important about modern equipment: electronics do not fail gracefully anymore.

In the analog days, equipment usually gave warnings before it died. Pumps slowed down. Lights dimmed. Heaters struggled to maintain temperature. You could often see failure coming before disaster struck.

Modern electronics tend to work perfectly right up until they don't. A light shuts off. A pump throws an error code. A heater quietly stops heating. A tank can go from thriving to struggling in a very short window when essential equipment suddenly fails.

That does not mean you should live in fear of your aquarium equipment. Failure is simply part of keeping enclosed ecosystems. The goal is not to prevent failure forever. The goal is to make failure survivable.

That means redundancy.

Heaters and pumps are some of the few pieces of equipment I try to replace proactively every few years. I do not really care how long a heater can last. I care how long I trust it before it becomes a risk. The old equipment usually gets cleaned up and stored away as emergency backups.

Filters, lights, and other non-critical equipment are worth keeping spares for as well. While your current setup is working, keep an eye out for good deals on replacement equipment. A shelf with tested spare aquarium gear can mean the difference between a minor inconvenience and a tank crash.

A mature aquarium should survive a bad day.

The biggest takeaway is not to distrust your equipment, but to give it the side-eye and play it safe.

External Organs

Mammals are an oddity in the animal kingdom.

We took nearly every variable that affects life and decided to control it internally. Temperature, waste management, even respiration to some extent—all handled inside the body. We took the tried-and-true method of laying eggs, looked at it, and said, “watch this,” then started developing offspring internally.

Humans, being mammals, carry a bias toward other mammals.

I once watched a podcast clip where one guy asked, “If you could fight any animal, what would it be?” The other answered: a fish—because it couldn’t fight on land. That somehow turned into an argument about whether fish even count as animals.

It sounds ridiculous, but it’s not surprising.

Even culturally, when we think “animal,” we think mammals. In The Wizard of Oz, Dorothy runs through the forest chanting, “lions and tigers and bears, oh my.” Large, dangerous, terrestrial mammals. The line works because we instinctively understand them as threats. It wouldn’t land the same if it were “spiders and leeches and brain-eating amoebas.”

This bias leaks directly into how people approach fishkeeping.

When someone gets a dog or a cat, the checklist feels simple: food, water, shelter. There’s more to it than that, of course, but it feels manageable. You don’t think about the oxygen content of your house. You don’t worry about whether your thermostat is within a degree or two. The animal handles most of that internally.

Fish don’t.

A fish doesn’t just live in water. It lives through it.

Fish evolved in large, stable bodies of water—systems where temperature, chemistry, and oxygen levels change slowly and predictably. That stability isn’t something the fish creates; it’s something the environment provides.

Because of that, fish never needed to internalize as much control as mammals did. They outsourced it.

The water around a fish is doing work that, in mammals, happens inside the body. It’s handling gas exchange, waste removal, and chemical balance in a way that’s so constant, so integrated, that it might as well be part of the animal.

Not literally—but functionally close enough.

The easiest way to think about it is this:

The water in your aquarium acts like external organs.

It’s not just where the fish lives. It’s part of how the fish works.

And that’s where beginners run into trouble.

A bowl of water or a very small tank doesn’t just “limit space”—it destroys stability. The smaller the volume, the faster everything changes. Temperature swings quicker. Waste builds faster. Oxygen drops more easily.

Now imagine something similar happening to you.

Imagine your blood suddenly accumulating waste, losing oxygen, and drifting out of balance—while you’re still expected to function normally. That’s what poor water quality looks like to a fish.

This is why the first step in diagnosing a problem is almost never the fish itself.

It’s the water.

Because the water is the most vulnerable “organ” the fish has.

Fish still have gills, kidneys, livers—all the usual internal structures. But those organs only work because the environment around them is doing the other half of the job.

Take that away, or let it fluctuate too much, and the system fails.

So when you’re keeping fish, you’re not just caring for an animal.

You’re maintaining the external systems that allow that animal to exist at all.

A Priest, a Rabbi, and an Atheist Walk Into an Aquarium...

While it sounds like a set up to a really bad joke, it ends up being how a lot of people want to stock their aquariums. The biggest failing comes from the fact that fish is a giant umbrella term that doesn't even really apply to a meaningful biological grouping. 

Think of it like this: a goldfish, a molly fish and a clownfish all bear the same fishy title, but they couldn't be more diverse. Goldfish come from thousands of years of captive breeding in Eastern Asia. They come from slow moving cooler bodies of water. Molly fish come from the deltas and estuaries of Central and Southern America. They tolerate water from fresh all the way to full marine, though typically prefer low end brackish, which is more salty than fresh but not full marine. Clownfish are from the Indo-Pacific region of the world, spanning from reefs in South Eastern Asia to Indonesia and down to Australia and even Polynesia. The water they come from is salty and stable. Salinity barely changes. pH stays consistent.

I've been asked before if these fish could go in the same tank. 

Behaviorally, sure—why not?

Physiologically, they don’t even speak the same language.

Reptiles are generally understood to be ecologically diverse. Fish get put into the same category because their care looks very similar, and they all have a similar body plan. 

That's definitely not to say that mollies don't do well in freshwater tanks or that goldfish don't mind a higher temperature. There is some flexibility to each fish, but stocking a tank should be a careful consideration of each species needs. They share a label, not a world.

Better, Not Perfect

Often, I help someone set up a tank and never hear from them again. Other times, I see them weeks later. It really just depends on timing.

Either way, it’s always a good sign when someone comes back for more supplies. It usually means the tank is working.

My favorites are the children. Full of wonder and not really too apt on arguing about what a fish needs. One kid sticks out, though. He's maybe 5 or so. His grandparents had agreed to get him a fish, but he knew there were constraints. His grandparents didn't seem to speak English as a first language, so he was mostly the point of contact. I helped him set up a tank and answered all his questions and got him the essentials. He was dead set on no filter. As they were checking out, I mentioned that it would be a really good upgrade in the future. His grandparents didn't mind and wanted to get one, anyway.

Fast forward a few weeks to today, and I see him and his grandpa in for some fish. They didn't mention any deaths, so that's always awesome. They ended up getting a pair of Mollies for their 5 gallon. 

While I would always recommend a bigger tank for Mollies, this was something I could let go. 

It's not really about these fish in this particular tank that I wanted to help guide his decisions.

Rather, it's about the next tank with the next fish. 

In the hobby, we tend to get caught up in absolutes. I am in no way suggesting that there shouldn't be high standards of husbandry with any animal. Rather, I'm suggesting that perhaps good enough is a good launch pad to better. Reality is not such that every betta will end up in a heated, filtered, planted 10 gallon tank. Ideal and realistic often don't match. 

What is worth it, though, is inspiring the next fish keeper with animals that live. I think about my first real tank. It was a 10 gallon tank. It was not cycled and I put 5 guppies in there. Those 5 guppies lived. They were around for a week, then a month, then a few more months. They survived my first upgrade. Then the next. 

Those guppies only lived about a year or less. Not their full lifespan by any means, but longer than any other fish I'd ever tried. They got me interested in so much more. They were the gateway to my current knowledge.

How many fish have died in your tenure of fish keeping? How much did you learn from that? How much more do you engage and want to learn more when things go right? 

I’ve killed more fish than I’d like to admit. Not because I didn’t care, but because I didn’t know yet. My childhood tanks weren’t heated, filtered, or even appropriately sized. That’s where most people start.

The goal isn’t to pretend that step doesn’t exist. It’s to move people through it faster, with fewer losses along the way.

So, no, it's not about the mollies being in a tank that might be too small. Of course it's not ideal, but it's inspiring. Every time those mollies interact with the kid, every time they eat and everything they do is going to help our little friend want to know more. 

It’s a good example of setting expectations, too. Not every fish fits every tank—and tanks need more than just water.

The real goal post for helping people with new aquariums is not to get them to an ideal place, but a better place. After all, we're still learning too.