The phrase "fish tank stuff" covers a lot of ground, from the essential equipment your fish need to survive to decorative accessories that are purely personal preference. If you're looking at what's for sale and trying to figure out what actually matters, the short answer is: filter, heater, water conditioner, and test kit first. Everything else is secondary.
This guide breaks down all the fish tank stuff you'll encounter for sale, separates the must-haves from the nice-to-haves, explains what each item does, and gives you real pricing so you can budget your setup without overspending.
The Non-Negotiables
These are the items where cutting corners causes fish to die.
Filter
Every aquarium needs filtration. The filter houses beneficial bacteria that convert ammonia (fish waste) into nitrite and then into nitrate, through a process called the nitrogen cycle. Without a filter, ammonia builds to toxic levels quickly.
For tanks up to 30 gallons, the AquaClear 30 ($35) and the Seachem Tidal 35 ($45) are the most consistently recommended hang-on-back filters in the hobby. Both have adjustable flow, large media compartments, and reputations for lasting years without issues.
For tanks 40 gallons and up, a canister filter like the Fluval 207 ($110) sits below the stand and handles more media volume for better biological filtration. The Eheim Classic 250 ($90) is a slightly more affordable option with comparable performance.
Don't buy a filter rated exactly for your tank size. A filter labeled "for tanks up to 30 gallons" may only move 150 gallons per hour, which is borderline. Get a filter rated for 1.5 times your tank volume to have adequate headroom.
Heater
For tropical fish (which covers the vast majority of what pet stores sell), you need water between 74 and 80 degrees Fahrenheit. Without a heater, you're relying on room temperature, which is usually too cold and fluctuates with seasons.
The Aqueon Pro 100W ($25 to $30) handles tanks up to 30 gallons and has a shatter-resistant outer casing. The Eheim Jager TruTemp 100W ($30 to $35) is more precise, holding temperature within 0.5 degrees of the set point. Both are reliable.
Pair any heater with a cheap digital thermometer ($5 to $8) to verify the heater is holding the right temperature. Heater thermostats can drift over time.
Water Conditioner
Tap water contains chlorine and chloramines that kill the beneficial bacteria in your filter and irritate fish gills. Add Seachem Prime (5ml per 50 gallons, $12 for 500ml) to your water before every fill. It also temporarily detoxifies ammonia and nitrite in emergencies, which makes it worth keeping on hand even after your tank is established.
Test Kit
The API Freshwater Master Test Kit ($25) gives you liquid drop tests for ammonia, nitrite, nitrate, and pH. These four parameters tell you almost everything you need to know about your water quality. Paper test strips are significantly less accurate and not worth the savings.
Maintenance Stuff
These are the items you'll use regularly to keep the tank clean and the fish healthy.
Gravel Vacuum
The gravel vacuum is your most-used maintenance tool. You siphon water out during water changes while simultaneously pulling debris out of the substrate. The Lee's 9-inch gravel vacuum ($8 to $10) works for small tanks. The Python No Spill Clean and Fill ($40 to $50) connects to your faucet and eliminates bucket hauling for medium and large tanks.
Weekly water changes of 25 to 30 percent with gravel vacuuming keep nitrate in check and the substrate clean. Without a gravel vacuum, waste accumulates in the substrate and slowly degrades water quality.
Algae Scraper
Algae grows on tank glass in any lit aquarium. A magnetic scraper lets you clean the glass without getting your arm wet. The Flipper Standard ($20 to $25) has both a scrubbing side and a smooth side and floats if you drop the interior magnet, preventing it from sinking and picking up gravel. For standard glass tanks, this is one of the more useful accessories you'll buy.
Net
Get two nets: a small 4-inch fine-mesh net for catching small fish and a larger 6-inch net for general scooping. You'll use them constantly. Most nets run $3 to $8 each.
Decor and Substrate Stuff
Gravel or Sand
Standard aquarium gravel in the 2 to 5mm range works for most community tanks and is easy to vacuum. Carib Sea Super Naturals gravel comes in natural-looking colors for about $15 to $20 per bag. Black Diamond blasting sand (pool/hardware stores) is a budget option for tanks where fish prefer sandy substrate, running about $10 for a 50-pound bag.
Plan on 1 to 2 pounds of substrate per gallon for a shallow layer. A 30-gallon tank needs 30 to 60 pounds.
Decorations
Fish need places to hide, especially when they're new to a tank. Ceramic caves, terracotta pots, driftwood, and smooth rocks all work. Live or silk plants provide cover without sharp edges.
Avoid cheaply painted resin ornaments that can leach paint into the water. Look for decorations labeled specifically as aquarium-safe. A modest decoration budget of $20 to $40 is enough to create good cover without overcrowding the tank.
For online sourcing of decor and accessories, the Best Online Fish Supply Store guide covers where to find the best selection and pricing on decorations, substrate, and accessories.
Lighting
Fish-only tanks need very little light. A basic LED strip or hood light that came with your tank kit works fine. Fish don't have specific light requirements the way plants and corals do.
If you want live plants, invest in planted-specific lighting. The Nicrew ClassicLED Plus ($30 to $50) provides adequate intensity for low and medium-light plants. The Finnex Planted+ 24/7 ($80 to $120) handles high-light planted tank setups.
Specialty Stuff Worth Knowing About
Air Pump and Air Stone
Air pumps add oxygen to the water through surface agitation. Most filter setups already handle this if they break the water surface, but an air pump with an air stone provides extra aeration. The Tetra Whisper AP series is quiet and reliable, running $10 to $20.
For air pump and oxygen system pricing, the Best Oxygen Machine for Fish Tank Price article breaks down every major option with notes on noise levels and coverage.
Automatic Feeder
If you travel, an automatic feeder like the Eheim Auto Feeder ($35 to $45) dispenses measured portions of dry food on a schedule. Fish can go 3 to 5 days without food without health issues, but for longer trips an auto feeder is much better than asking a neighbor who may dramatically overfeed.
Quarantine Tank
A separate small tank (10 gallons works) used to isolate new fish before adding them to your main tank is one of the most valuable pieces of fish tank stuff most people never buy. New fish can carry parasites or disease that infects your entire established tank. A 2 to 4 week quarantine period eliminates most of this risk.
A cheap 10-gallon glass tank, a sponge filter, and a small heater is all you need. Keep a sponge filter running in your main tank permanently so it stays seeded with beneficial bacteria and is always ready for quarantine duty.
What You Don't Need
Aquarium salts for freshwater tanks: Advertising suggests this reduces stress and promotes healing. For most freshwater community fish, it does more harm than good. Goldfish and some livebearers tolerate small amounts, but tetras, corydoras, and most other popular species prefer salt-free water.
"Instant cycle" products with bold claims: Some work partially. Seachem Stability and API Quick Start contain live bacteria and do help seed a filter faster. Products that claim to cycle a tank in 24 hours are mostly hype. A proper cycle takes 2 to 6 weeks.
Oversized decorations that fill half the tank: Fish need swimming space. A common mistake is cramming a 20-gallon tank full of large ornaments, leaving fish with only a few small paths to swim through.
Tank dividers for aggressive fish: They work temporarily but don't solve underlying compatibility issues. Two territorial fish that can see each other through a divider often glass-surf and stress as if the divider isn't there.
FAQ
What fish tank stuff do I need to buy first? In order: filter, heater, water conditioner, and test kit. Run the filter for 4 to 6 weeks with no fish to cycle the tank. Then add substrate, decorations, and finally fish.
How much does basic fish tank stuff cost? A complete basic 20-gallon freshwater setup including equipment, substrate, decorations, and a few fish runs $250 to $400 new. Buying the tank and stand used and purchasing equipment new brings that total down to $150 to $250.
Where can I find cheap fish tank stuff? Dollar-per-gallon sales at Petco and PetSmart are the best times to buy tanks. Amazon and Chewy offer the best online prices on equipment and consumables. Facebook Marketplace has the best deals on complete used setups. Specialty stores are worth visiting for livestock and advice even if their equipment prices are higher.
What's the most overpriced fish tank item? Premium carbon-based filter media inserts that come pre-loaded in some filter cartridges. Activated carbon does a specific job (removing odors, medications, and discoloration) but doesn't need to be replaced every month. Most experienced fish keepers remove the carbon insert and replace it with additional biological media. The replacement cartridge business model benefits the manufacturer more than the fish keeper.