Aquarium Fish Interesting Facts for Beginners and Enthusiasts

Why Choose Aquarium Fish as Pets

A pet doesn’t have to mean noise and mess. Aquarium fish are peaceful inhabitants that have a calming effect on their owners. In my experience, watching the smooth, graceful movements of fish helps relieve stress after a long workday.

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Tank Selection: Size Matters

Aquariums come in all shapes and sizes to suit different preferences and living spaces. The world’s smallest aquarium measures just 3 cm long and 1.5 cm wide—barely enough for a couple of tiny fish, plants, and pebbles. This is more of a publicity stunt than a proper home for aquatic life.

If your space allows, you can choose virtually any tank size. However, don’t forget: while fish are quiet, they require diligent care. Some species are particularly demanding regarding water parameters and environmental conditions.

Miniature aquarium with tiny fish and decorations — The world’s smallest aquarium—more of a novelty than a practical habitat for fish

Aquarium Fish Interesting Facts About Keeping

Small rectangular desktop aquarium with a single goldfish — A typical office aquarium setup with a goldfish in a small rectangular tank

Offices often feature one or two fish in small round or rectangular tanks. These are frequently goldfish varieties, such as veiltails. I recommend avoiding round bowls—they distort fish vision and don’t provide adequate surface area for gas exchange.

Setup and Equipment Essentials

For substrate, medium-grain gravel (3-5 mm) works better than fine sand. With each cleaning and siphoning session, fine sand gradually depletes, while larger gravel remains stable.

Live plants are preferable to artificial ones—they participate in biological balance, absorb nitrates, and release oxygen. This creates a more natural appearance and benefits the inhabitants.

Fish are aquatic creatures, but they still need oxygen. Your aquarium should have either an aeration system or quality filtration that creates water movement at the surface.

Species Compatibility and Tank Mates

Some fish species are completely incompatible and will engage in deadly conflicts. For example, aggressive cichlids like the flamingo cichlid (Cichlasoma sp.) cannot coexist with small peaceful species. If you’re uncertain about compatibility, always consult specialists or study reliable sources.

Besides fish, aquariums can house snails (apple snails, nerites), shrimp, and even aquatic frogs. In my experience, cleanup crew shrimp do an excellent job controlling algae growth.

Peaceful community fish like black mollies can share space with similar-sized, non-aggressive species, creating a harmonious underwater environment.

Critical Care Guidelines

Aquatic frog resting in aquarium environment — Aquatic frogs can be kept alongside fish as alternative aquarium inhabitants

Lighting: Never allow direct sunlight to hit your aquarium—this triggers explosive algae growth and water overheating. Use dedicated aquarium lights with a timer instead.

Feeding: Overfeeding kills fish. A single overfeeding incident can cause ammonia poisoning from decomposing leftovers. I recommend feeding adult fish once daily with portions they consume within 2-3 minutes.

Observation and Relaxation: Watching fish glide smoothly through water calms nerves and lowers blood pressure. This living picture truly relaxes—no wonder aquariums appear in medical facilities and offices.