The essential fish aquarium supplies are a tank, a filter, a heater, a thermometer, a water conditioner, test kits, a light, and substrate. Those eight things cover the biology and chemistry your fish need to survive and stay healthy. Everything else, from decorations to air pumps to automated feeders, is either optional or something you add as your tank and knowledge develop.
Most beginners overspend on decorations and underspend on filtration. A cheap filter will cost you more in fish losses than any decoration ever saves. Getting the core supplies right from the start is the most important investment you'll make in the hobby.
Filtration: The Most Important Supply You'll Buy
A filter runs 24 hours a day, 7 days a week, maintaining the beneficial bacteria that convert fish waste (ammonia) into progressively less toxic compounds through the nitrogen cycle. Ammonia kills fish quickly. Nitrite, the next stage, kills almost as fast. Nitrate is relatively safe at lower levels and is removed through water changes.
The filter needs to match the tank size and fish load. Most manufacturers rate their filters for a specific gallon range, but those ratings are optimistic. For a heavily stocked tank or one with large, messy fish like goldfish, cichlids, or oscars, size up significantly.
Hang-On-Back Filters
HOB filters are the most practical choice for most home aquariums. They're easy to service, hold enough media to support a healthy bacterial colony, and don't require tubing or a canister.
The Aquaclear series (Aquaclear 30 for tanks up to 30 gallons, Aquaclear 50 for up to 50 gallons, Aquaclear 70 for up to 70 gallons) has an excellent reputation for reliability and media flexibility. The media chamber is larger than most competing brands, which supports a bigger bacterial colony. Seachem Tidal filters self-prime (convenient after water changes or cleaning) and include a surface skimmer to remove the protein film that forms on still water.
Canister Filters
For tanks 75 gallons and larger, canister filters hold significantly more media and push more water. The Fluval 407 (rated for 100 gallons) and Fluval 507 (rated for 156 gallons) are reliable choices with good maintenance intervals. Eheim Classic series canisters (Eheim 2215, 2217) are known for near-silent operation and durability over many years.
Sponge Filters
For dedicated breeding tanks, quarantine setups, or small fry tanks, sponge filters are the right choice. They provide gentle filtration without creating flow that can injure small fish or eggs. Connecting a sponge filter to an established tank's air pump seeds it with bacteria quickly, making it useful for setting up emergency hospital tanks.
Heating and Temperature Control
Most tropical fish need water between 74 and 80 F. Without a heater in most homes, tank water will be several degrees cooler than the room, and room temperature fluctuates with seasons. A heater maintains stable temperature, which is important because fish immune systems are sensitive to temperature swings.
The sizing guide: 3 to 5 watts per gallon of tank water. A 40-gallon tank needs a 120 to 200-watt heater. For tanks over 40 gallons, using two heaters rated for the full volume is safer than one: if one fails in the heating position, the tank is less likely to reach lethal temperatures. If one fails in the off position, the backup maintains warmth.
The Aqueon Pro line (75W, 100W, 150W, 200W, 300W) includes a thermal cutoff that prevents overheating. Cobalt Aquatics Neo-Therm heaters are accurate, flat (easier to hide), and have a good failure rate record. Eheim Jager heaters allow you to recalibrate the setpoint against an accurate thermometer, which is useful for breeding setups that need precise temperature control.
Always use a separate thermometer to verify the heater is maintaining the correct temperature. Internal heater calibration drifts over time, and built-in temperature displays are often inaccurate.
Water Conditioning and Chemistry Supplies
Tap water must be dechlorinated before it goes into a fish tank. Chlorine and chloramines kill fish and beneficial bacteria. Seachem Prime is the most cost-effective conditioner available: one capful (5 mL) treats 50 gallons, it detoxifies ammonia and nitrite for 24 to 48 hours in addition to neutralizing chloramines, and a 500 mL bottle costs about $12 and lasts for thousands of gallons.
Test Kits
Accurate test results let you understand what's happening in your tank chemistry before it becomes visible as sick or dead fish.
The API Freshwater Master Test Kit covers ammonia, nitrite, nitrate, and pH for about $25. It includes enough reagents for over 700 tests. Use it weekly for the first three months of a new tank to track the nitrogen cycle, and monthly once the tank is established. Salifert test kits provide better precision for pH, KH, and GH if you're keeping species with specific water chemistry requirements (discus, African cichlids, or soft-water species).
For planted tanks, you'll also want to test for CO2 (drop checker), iron (Seachem or Salifert iron test), and potassium if you're running a high-tech setup.
Lighting Supplies
Fish-only tanks need enough light to observe your fish and maintain a day-night cycle. 8 to 10 hours of LED light per day is standard. A basic LED hood or clip-on LED (Aqueon LED Full Spectrum Clip-On, Nicrew ClassicLED) is sufficient for viewing fish and supporting minimal or artificial plants.
Planted tanks need more. The intensity (PAR, photosynthetically active radiation) at the substrate determines which plants you can grow.
- Low light (under 30 PAR): Anubias, java fern, hornwort, mosses
- Medium light (30 to 50 PAR): Cryptocorynes, most stem plants, amazon sword
- High light (50+ PAR): Carpeting plants, demanding Bucephalandra species, Rotala colorata
The Fluval Plant 3.0 and Finnex Stingray are popular planted tank lights that cover low to medium light needs. The Chihiros WRGB II and Fluval Plant 3.0 on high settings reach the upper range for demanding plants.
Timers (even simple $5 mechanical outlet timers) are worth using to maintain a consistent photoperiod.
Substrate and Decoration Supplies
Plain aquarium gravel works for fish-only tanks. It's inert, easy to clean, and available in various colors. Rinse it thoroughly before use.
Sand substrate (1 to 3 inches) is better for bottom-dwelling fish like corydoras, loaches, and many cichlids that naturally sift through it. Pool filter sand from a hardware store costs about $10 for 50 pounds and is functionally identical to expensive aquarium sand.
For planted tanks, nutrient-rich substrates support root growth more effectively than inert gravel. Fluval Stratum, CaribSea Eco-Complete, and ADA Amazonia are well-regarded planted tank substrates at different price points.
Decorations and Hardscape
Fish need places to hide, rest, and establish territories. Natural driftwood and rocks look good and can serve functional purposes: wood releases tannins that soften and acidify water (good for bettas and soft-water species), and rock provides territory markers for cichlids. Malaysian driftwood and spider wood are popular choices.
Artificial decorations work fine as long as the edges are smooth. Avoid anything with sharp points that can tear fins, and rinse all decorations before adding to the tank.
Maintenance Supplies
Regular maintenance keeps water quality high and catches problems before they escalate.
A gravel vacuum siphon removes waste from the substrate during water changes. The Python No Spill Clean and Fill connects to a faucet and lets you vacuum and refill in one step without carrying buckets. For tanks under 40 gallons, a basic Lee's Ultimate Gravel Vacuum siphon costs about $10 and works well.
A magnetic algae scraper (Flipper Nano, Flipper Standard) cleans algae from the glass without putting your hands in the tank. The Flipper Standard handles glass up to 3/8 inch thick. For acrylic tanks, use a scraper without metal blades.
Keep a dedicated 5-gallon bucket used only for aquarium water changes. Residue from cleaning products in shared buckets is toxic to fish.
For the best sources on where to buy aquarium supplies at competitive prices, our Best Online Fish Supply Store guide covers the most reliable vendors for both livestock and equipment. If you're adding aeration to your tank setup, the guide on oxygen machine for fish tank price covers what air pumps cost and how to size them.
FAQ
What's the minimum I need to spend to set up a healthy fish tank?
A 20-gallon freshwater tank with a quality HOB filter (Aquaclear 30), basic heater, thermometer, light, test kit, and dechlorinator runs about $150 to $200. Adding substrate and a few decorations brings it to $200 to $250 before fish. You can spend more for better equipment, but this budget covers all the essentials.
Do I need a quarantine tank?
Every experienced fish keeper recommends having one. A quarantine tank (a simple 10 to 20-gallon tank with a sponge filter and heater) lets you observe new fish for 2 to 4 weeks before introducing them to your display tank. This prevents common parasites like ich and velvet from spreading to fish you've already established. It doesn't need to be running full-time; store the sponge filter in your display tank between uses to keep it seeded with bacteria.
How often should I do water changes?
For most freshwater tanks: 20 to 25 percent weekly. For heavily stocked tanks with large fish: 25 to 30 percent weekly. For lightly stocked planted tanks: 10 to 15 percent weekly. Consistency matters more than exact percentage. Missing water changes lets nitrate accumulate and conditions deteriorate.
What supplies do I need for a betta fish specifically?
Bettas need a minimum 5-gallon tank (10 gallons is better), a gentle filter (strong flow stresses bettas), a heater to maintain 78 to 80 F, a lid (bettas jump), and soft decorations without sharp edges that tear their fins. A simple sponge filter or low-flow HOB works well. Bettas are labyrinth fish and breathe surface air, so surface access is important.
Starting Right
Prioritize the filter above everything else. A cycled filter with a healthy bacterial colony is what keeps your fish alive between water changes. After that, a reliable heater and water conditioner protect against the two most common causes of new fish loss: temperature stress and chlorine toxicity. Get those three things right, and the rest of the supply list fills in naturally as your tank develops.