The fish tank aquarium supplies you truly need boil down to six categories: filtration, heating (for tropical species), lighting, substrate, water treatment, and testing equipment. Everything else is optional or species-specific. If you're building a new setup or filling gaps in an existing one, knowing what each piece of equipment does and why it matters saves you from wasting money on gear that collects dust.
This guide covers the essential supply categories with specific product recommendations, the numbers to know when sizing equipment, the difference between freshwater and saltwater supply lists, and the common mistakes beginners make when buying gear for the first time.
Filtration: The Single Most Important Purchase
The filter is the heart of any fish tank. It runs every minute of every day, maintaining the biological cycle that keeps your fish alive. Skimping here causes more fish deaths than any other equipment decision.
Aquarium filters handle three types of filtration:
Mechanical filtration traps particles. Debris, uneaten food, and fish waste get caught in sponge or filter floss before they decompose and raise ammonia.
Biological filtration is where the real magic happens. Beneficial bacteria colonize your filter media and convert toxic ammonia (from fish waste and uneaten food) into nitrite, then into the less harmful nitrate. This is called the nitrogen cycle, and your filter media is where it lives. Never replace all your filter media at once, or you destroy this colony and have to start the cycle over.
Chemical filtration uses activated carbon or other media to absorb dissolved toxins, medications, and discoloration. It's useful in specific situations (clearing cloudiness after using medication, removing tannins from driftwood) but not essential for established, healthy tanks.
Filter Types and When to Use Each
Hang-on-back (HOB) filters are the best starting point for most setups. The Aquaclear 30 ($35) for tanks up to 30 gallons and the Aquaclear 70 ($55) for up to 70 gallons are the most recommended options in the hobby for reliability and ease of maintenance. Media is customizable, flow rate is adjustable, and cleaning takes five minutes.
Canister filters are better for 40+ gallon tanks and planted setups. The Fluval 207 ($90) handles up to 45 gallons, the Fluval 307 handles up to 70 gallons. Canister filters hold more media volume, run quieter, and only need cleaning every 2-3 months. The tradeoff is more complex setup and slightly higher cost.
Sponge filters are perfect for tanks under 20 gallons, breeding tanks, and quarantine setups. They're gentle enough for fry and shrimp, nearly impossible to break, and cost $5-15. They require an air pump to run.
Internal filters like the Fluval U series work well for nano tanks and as secondary filtration for larger setups.
Size your filter for at least 5-10 times your tank volume in gallons per hour (GPH) turnover. A 30-gallon tank needs a filter rated for at least 150-300 GPH.
Heating and Temperature Control
Tropical fish need water between 74-80°F. A reliable heater isn't a luxury for these species, it's mandatory. Temperature drops below 68°F stress most tropical species and open the door to ich and other parasitic infections.
The Eheim Jager series is the benchmark for reliability. The 100W model suits tanks up to 35 gallons, the 150W handles 35-50 gallons, and the 200W covers 65-80 gallons. Jager heaters have a recalibration dial to ensure the thermostat stays accurate over time.
The Aqueon Pro heater is another solid choice at a slightly lower price point. It uses a shatterproof outer casing and has an LED indicator that changes color when heating vs. Holding temperature.
Size at 3-5 watts per gallon. A 50-gallon tank needs 150-250 watts. In a cold room (under 68°F) lean toward the higher end.
Always use a separate thermometer to verify your heater's accuracy. Heater thermostats drift, and a heater reading 2-3°F low while actually delivering high heat can cook your fish. A simple glass thermometer costs $3. An Inkbird IBS-TH2 Wi-Fi thermometer that alerts your phone when temperature goes out of range costs $15 and is worth every penny for expensive livestock.
Water Treatment and Chemistry
Tap water contains chlorine or chloramine, both of which are lethal to fish and will kill the beneficial bacteria in your filter. A water conditioner must be added every time you do a water change.
Seachem Prime is the standard recommendation. It dechlorinates instantly, detoxifies ammonia and nitrite temporarily (useful during cycling), and a tiny 1 mL dose treats 10 gallons. A 100 mL bottle ($7) lasts months in most setups.
The API Freshwater Master Test Kit ($25-30) is the other non-negotiable purchase. It tests pH, ammonia, nitrite, and nitrate with liquid reagents that are far more accurate than test strips at the low concentrations where problems begin. Test strips are fast but regularly give false negatives on 0.25 ppm ammonia, the range where your fish are stressed but not yet visibly sick.
For saltwater tanks, a refractometer measures specific gravity (salinity). The Milwaukee MA887 runs about $30 and is accurate enough for both fish-only and reef tanks.
Buffering products like API pH Up/Down or Seachem Alkalinity Neutral Regulator let you adjust pH if your tap water runs too acidic or alkaline for your fish. Most community tropical fish tolerate pH 6.8-7.8, so unless you're keeping soft-water species (discus, cardinal tetras) or hard-water species (African cichlids, livebearers), you may not need these at all.
If you're sourcing supplies online, the best online fish supply store guide compares pricing and selection to help you find the best deals on water treatment products and test kits.
Substrates and Decorations
Substrate is both functional and aesthetic. It provides surface area for beneficial bacteria, anchors plants, and affects the natural behavior of bottom-dwelling fish.
Standard aquarium gravel in 3-5mm size is the easiest to maintain and works well for most community fish. CaribSea Super Naturals and Imagitarium brands offer good variety at $10-20 per 20-pound bag (enough for 2-3 inches in a 20-gallon tank).
Fine sand (1-2mm) is ideal for corydoras, loaches, and other species that dig or sift through substrate. These fish can injure their barbels on coarse gravel. Pool filter sand is a popular cheap option at $6-8 per 50-pound bag, though it needs thorough rinsing before use.
Planted substrates like Fluval Stratum, Seachem Flourite, or ADA Amazonia provide nutrients that plant roots absorb directly. They cost more ($15-35 per bag) but produce noticeably better plant growth than inert gravel in planted setups.
Decorations provide shelter and territory boundaries. Caves, hollow logs, and dense plant clusters reduce aggression in territorial species and allow shy fish to establish routines. A tank with no hiding spots produces visibly stressed fish. Aim for at least one hiding spot per fish in territorial species, and clusters of cover throughout the tank.
Lighting for Fish and Plants
Light requirements vary by what you're keeping.
For fish-only freshwater tanks, any full-spectrum LED that provides 8-10 hours of light per day works fine. The Nicrew ClassicLED ($25 for 24") and Fluval Aquasky 2.0 are both reliable and bright enough for non-planted setups.
Planted tanks need more intensity and the right spectrum. Look for LEDs in the 5000-7000K color temperature range. PAR values above 30 at substrate level support low-light plants (java fern, anubias), while high-light plants like carpeting species need PAR above 80. The Fluval Plant 3.0 and Finnex Planted+ 24/7 both deliver high PAR with customizable intensity and scheduling.
Coral in reef tanks has the highest light demands. Many SPS corals need PAR of 200-400+ at the coral placement level. Dedicated reef LEDs like the AI Prime HD or Kessil A360 are designed for this.
Aeration and Oxygen
Surface agitation from your filter is usually enough for oxygenation in well-stocked tanks. But heavily stocked tanks, tanks with warm water (oxygen solubility drops as temperature rises), and species with high oxygen needs can benefit from supplemental aeration.
Air pumps with airstones add dissolved oxygen through gas exchange at the water surface. The Tetra Whisper 40 handles tanks up to 40 gallons at under $15. You'll need airline tubing and a check valve to prevent back-siphon when the pump turns off.
For dedicated oxygen equipment comparisons and pricing, see the oxygen machine for fish tank price guide.
FAQ
What's the minimum equipment needed to keep fish alive?
Realistically: a filter, a heater (for tropical species), a light on a timer, water conditioner, and a test kit. That covers the basics. Substrate and decorations make the tank safer and healthier for the fish, so they're worth including, but the first five are what keep your fish alive.
How much does a complete fish tank supply setup cost?
A basic freshwater community tank setup (tank, filter, heater, light, substrate, conditioner, test kit) runs $150-250 for a 20-30 gallon setup with quality equipment. You can set up a nano tank for $80-100 with budget gear, or spend $500+ on a high-end planted tank build. Saltwater setups start at $400-500 minimum for a small fish-only tank and scale up quickly.
Do I need to cycle the tank before adding fish?
Yes, always. The nitrogen cycle establishes beneficial bacteria that convert toxic ammonia into less harmful compounds. Skipping this step causes "new tank syndrome," where ammonia spikes to lethal levels within days of adding fish. A fishless cycle using ammonia dosing takes 4-6 weeks. A fish-in cycle using hardy species and daily water changes takes 4-8 weeks and is more stressful for the fish.
Can I reuse old fish tank supplies?
Filter media, heaters, and pumps can be reused if they still function correctly. Sterilize them thoroughly with a bleach solution (10:1 water:bleach), rinse extremely well, and let them dry before reusing. Substrate can be reused if it doesn't contain a disease or parasite history. Some keepers avoid reusing substrate after a tank crash involving ich or other persistent parasites.
Key Takeaways
Buy quality equipment where it counts most: the filter, heater, and test kit. These three pieces directly determine whether your fish live or die. Lighting matters a lot for planted tanks and is more flexible for fish-only setups. Substrate choice affects both aesthetics and the health of bottom-dwellers and plants. Don't skimp on water conditioner, and never add tap water to a tank without dechlorinating it first. Once those fundamentals are in place, you can add supplemental equipment based on what you're keeping.