You know, after thirty-two years of dealing with medical emergencies where split-second decisions meant life or death, you’d think I’d be better at researching before jumping into something new. But when I first got serious about aquascaping after retirement, I made every rookie mistake in the book when it came to fish compatibility. Let me tell you, watching fish stress each other out in what should be a peaceful environment was way too reminiscent of the chaos I’d left behind in the ER.
My granddaughter had been asking for that fish tank, and I figured how hard could it be? I mean, fish are fish, right? Wrong. So very wrong. I remember standing in that Petco, picking out what I thought were pretty fish that would look nice together. A beautiful betta with those flowing fins – he was gorgeous. Some colorful tetras. A few other community fish the teenager working there said would be “fine together.” Within a week, my peaceful little underwater garden had turned into something that looked more like a bar fight.
That betta, despite being absolutely stunning, was terrorizing everything else in the tank. The poor tetras were hiding behind plants, fins getting nipped, clearly stressed out of their minds. I’d sit there in the evenings – you know, during what was supposed to be my relaxing decompression time – and instead I’m watching this aquatic version of workplace bullying happening right in my living room. It was the exact opposite of the calm, meditative experience I was hoping for.
That first disaster taught me something important though. Just like in nursing where you couldn’t just throw random medications together and hope for the best, you can’t just mix random fish species and expect harmony. There’s actual science behind this stuff, and ignoring it leads to problems. Sometimes fatal ones.
I ended up having to completely restart that first tank, but this time I did my homework. Spent weeks reading about temperament, water requirements, feeding needs, territorial behaviors – all the stuff I should have researched before buying a single fish. My husband kept joking that I was studying harder for this hobby than I had for my nursing boards, and honestly, he wasn’t wrong.
The research phase was actually kind of fascinating once I got into it. Fish have personalities, just like people do. Some are aggressive bullies, some are shy wallflowers, some are peaceful community-minded types. Some prefer to hang out near the surface, others stick to the bottom, some patrol the middle areas. It’s like understanding the social dynamics of a workplace, except with fins.
I decided to focus my second attempt on South American species that naturally lived together in the wild. Figured if they got along in the Amazon basin, they’d probably manage okay in my 55-gallon tank. Did a ton of research on cardinal tetras – gorgeous little fish that school together beautifully. Added some corydoras catfish because they’re bottom-dwellers and wouldn’t compete for the same space. Found a peaceful dwarf cichlid that could handle the same water parameters without terrorizing the smaller fish.
Setting up that second community tank was like planning a really good nursing shift assignment – you want personalities that complement each other, skill levels that don’t clash, people (or fish) working in different areas so they’re not stepping on each other’s toes. The difference was, if I messed up a shift assignment, someone might have a bad day at work. If I messed up a fish community, someone might literally die.
This time it worked. The cardinals swam in this beautiful red and blue school, the corys spent their time happily rooting around the bottom keeping things clean, and the little apistogramma claimed a small territory near a piece of driftwood but left everyone else alone. It was exactly the peaceful, living artwork I’d been hoping for from the beginning.
But getting there required understanding way more than I’d expected about fish behavior. Turns out size matters a lot – not just because big fish might eat little fish, though that’s definitely a concern. Even peaceful larger fish can stress out smaller species just by being… well, large and active. I learned this when I added some bigger peaceful barbs to a tank with tiny microrasboras. Nobody got eaten, but those little guys spent all their time hiding because they were constantly startled by fish that were just going about their normal business.
Water chemistry was another learning curve. Different species evolved in different environments, and what feels like home to one fish might be completely wrong for another. Goldfish like cooler water, most tropical fish need it warmer. Some prefer soft, acidic water like they’d find in the Amazon. Others want hard, alkaline water like African rift lakes. Mixing fish with completely different requirements is like trying to make desert plants and rainforest plants happy in the same greenhouse – it’s just not going to work well.
I made the mistake once of adding some African cichlids to a tank with South American species because they were similar sizes and both were cichlids, so how different could they be? Pretty different, as it turned out. The water parameters that kept my South Americans healthy were all wrong for the Africans, and vice versa. Nobody thrived, everyone was stressed, and I eventually had to set up separate tanks.
Feeding turned out to be more complicated than I’d expected too. Some fish are aggressive eaters that’ll gobble up food before shyer species get a chance. Some need live or frozen foods, others are fine with flakes. Herbivorous fish might nibble on your carefully planned aquascape plants, which was particularly annoying when I’d spent good money on rare species.
I developed this whole feeding routine – sinking pellets for the bottom-feeders dropped right where they hung out, floating flakes for the surface fish, sometimes frozen bloodworms for fish that needed more protein. Had to time it so the fast eaters didn’t steal everything before the slower fish got their share. It was like managing dietary restrictions and meal timing for multiple patients, except these patients had fins and couldn’t tell me if something was wrong.
The activity level thing was something I hadn’t considered at all initially. Some fish are constantly on the move, others prefer to cruise slowly, some barely move at all during the day. Mixing hyperactive species with calm ones can stress everyone out. It’s like putting a marathon runner in a meditation retreat – nobody’s going to be comfortable.
I found that thinking about the tank in layers helped a lot. Surface fish, middle-water fish, bottom fish – each group has their preferred zone and mostly stays there. A good community tank has something happening at each level without overcrowding any particular area. My most successful tanks have had hatchetfish or surface-dwelling gouramis up top, schooling tetras or rasboras in the middle, and corydoras or plecos on the bottom.
Even after doing all this research and planning, I learned that observation is absolutely critical. Fish have individual personalities beyond their species characteristics, and sometimes you get surprises. I had one cardinal tetra who turned into a total bully despite being from a supposedly peaceful schooling species. One angelfish who was completely docile despite angels having a reputation for being aggressive as they mature. You can research all you want, but you still need to watch your actual fish and be willing to make changes.
The monitoring aspect actually appealed to my nursing background. I was used to watching for subtle signs that something was off – changes in behavior, appetite, coloration, breathing patterns. Early intervention in a fish tank, just like in healthcare, usually means the difference between a minor adjustment and a major crisis.
I’ve had to rehome fish that didn’t work out in particular communities, despite my best planning. It’s not a failure – it’s just recognizing that sometimes personalities don’t mesh, or growth changes the dynamics, or you discover something about your water or setup that doesn’t work for a particular species. Better to find a fish a more suitable home than watch it be stressed or stressed others.
My current setup includes three different community tanks, each with its own theme and carefully selected inhabitants. One South American blackwater setup, one Southeast Asian tank, and one Lake Malawi cichlid tank. Each one has completely different fish, different water parameters, different feeding schedules, different maintenance needs. It sounds complicated, but the routine has become part of my daily structure, and honestly, it’s so much more relaxing than the chaos of that first failed attempt.
The whole experience taught me that successful fish keeping isn’t just about creating something beautiful – though that’s definitely part of it. It’s about understanding that you’re responsible for these living creatures and their quality of life depends entirely on the decisions you make about their environment and tankmates. That’s a responsibility I don’t take lightly, even though the stakes are obviously different from my nursing days.
A retired ER nurse, Elena found peace in aquascaping’s slow, steady rhythm. Her tanks are quiet therapy—living art after years of chaos. She writes about learning, patience, and finding calm through caring for small, beautiful ecosystems.
