Aquarium Fish & Supply

Setting up an aquarium successfully comes down to pairing the right fish with the right supplies. The core supplies every aquarium needs are a tank and stand, a filter appropriate for the tank volume, a heater (for tropical fish), lighting, a substrate, a thermometer, a water conditioner, and a test kit. Beyond those fundamentals, specific fish require specific equipment: cichlids need harder water and cave decorations, planted tanks need fertilizer and CO2, reef tanks need protein skimmers and calcium supplementation. The list grows with your ambitions.

This guide covers the essential supply categories and how to choose correctly for the fish you want to keep. I'll include specific products where they make a meaningful difference, because "buy a filter" isn't useful advice if you don't know which type or size.

The Core Equipment Categories

Filtration

Filtration is non-negotiable. Fish produce ammonia continuously through respiration and waste, and without beneficial bacteria to convert that ammonia to nitrite and then to nitrate, water becomes toxic within days in a new tank.

For most freshwater community tanks, a hang-on-back (HOB) filter rated for 1.5 to 2 times the actual tank volume is the standard starting point. The Aquaclear 70 for tanks up to 70 gallons and the Fluval C4 for tanks up to 50 gallons are both well-regarded and easy to service. They use mechanical foam pads, activated carbon, and bio-media that you can customize for your needs.

Canister filters work better for larger tanks (55 gallons and up) or tanks with significant bioload. The Fluval 307 for 45 to 70-gallon tanks and the Eheim Classic 2217 for 50 to 92-gallon tanks are reliable long-term choices with good media capacity. Canister filters go longer between servicing than HOB filters because of their larger media volume.

For planted tanks or breeding setups, sponge filters powered by an air pump provide gentle filtration that won't suck up eggs, fry, or delicate shrimp. The Hikari bacto-surge sponge filter is a solid pick for breeding tanks and shrimp tanks.

Heating

Most tropical fish thrive between 76 and 82 degrees Fahrenheit. The room temperature in most homes (68 to 72 degrees Fahrenheit) is too cold without a heater. For a community tank with guppies, tetras, or corydoras, a submersible heater rated for your tank volume keeps temperature stable.

The Eheim Jager TruTemp series is the benchmark for accuracy. The 100-watt model handles tanks up to 40 gallons; the 150-watt version covers up to 60 gallons; and the 300-watt handles 80 to 100-gallon tanks. Stick to 3 to 5 watts per gallon of tank volume as a sizing guide.

Pair any heater with a separate thermometer. The Zacro digital aquarium thermometer with a hanging probe gives real-time temperature and costs around $8.

Lighting

Lighting requirements depend on what you're keeping. Fish-only tanks can use any light that makes the fish look good and supports a natural day/night cycle. An 8 to 10-hour photoperiod with a timer is the simplest approach.

Planted tanks need light appropriate for the plants you're growing. Low-tech planted tanks with easy plants like Java fern, Anubias, and crypts grow well under 20 to 40 PAR (photosynthetically active radiation) at the substrate. Demanding stem plants or high-tech setups need 50 to 100+ PAR. The Fluval Plant 3.0 and the Chihiros RGB series are popular choices that deliver strong performance at mid-range prices.

For reef tanks, lighting requirements escalate significantly. SPS (small-polyp stony) corals need 100 to 300+ PAR, and appropriate coral-spectrum LED fixtures like the Aqua Illumination Hydra 26 HD or the Kessil A360X are the industry standard for serious reef keeping.

Fish Selection and Compatibility

The fish you choose determine almost every other supply decision. Aggressive cichlids need different tank decor (caves, territories) and different tank mates than peaceful community tetras. Coldwater fish like goldfish don't need a heater. Brackish species like archer fish need specific salinity management.

Community Fish

Common community fish like neon tetras (Paracheirodon innesi), guppies, mollies, corydoras catfish, and dwarf gourami are relatively forgiving and compatible with each other. A 20 to 30-gallon community tank with appropriate filtration and a heater provides a manageable environment for beginners.

School fish like tetras and rasboras need groups of at least 6 to exhibit natural behavior. A single neon tetra in a tank is stressed and more susceptible to disease than one kept in a school of 10 to 15.

Species-Specific Needs

Bettas (Betta splendens) need a tank of at least 5 gallons with a gentle filter (they don't like strong currents) and a heater set to 78 to 80 degrees Fahrenheit. Two male bettas cannot be housed together.

African cichlids from Lake Malawi or Tanganyika need hard, alkaline water (pH 7.8 to 8.5), specific rock or shell decor depending on species, and larger tanks to accommodate territory. A 55-gallon minimum is appropriate for most community cichlid setups.

Discus (Symphysodon aequifasciatus) are highly sensitive to water quality and need very soft, acidic water (pH 5.5 to 6.8, low hardness) kept at 84 to 86 degrees Fahrenheit. They are not beginner fish.

Water Quality Supplies

Test Kits

Testing water is how you know what's actually happening in your tank. The API Freshwater Master Test Kit covers the four essential parameters: ammonia, nitrite, nitrate, and pH. Test weekly during the first month of a new tank and monthly thereafter once the tank is established.

For saltwater tanks, add tests for alkalinity, calcium, and magnesium if you're keeping corals. Salifert profi test kits are accurate and widely used for reef water chemistry.

Water Conditioner

Tap water contains chlorine and often chloramine, both of which are toxic to fish. Seachem Prime neutralizes both and also temporarily detoxifies ammonia, giving you a buffer during high-ammonia situations. The 500 mL bottle treats 5,000 gallons and lasts most hobbyists a year or more.

Salt (for Marine Tanks)

Reef Crystals and Red Sea Coral Pro are the two most popular reef salts. Instant Ocean is the budget-friendly option for fish-only saltwater tanks. Mix salt to a specific gravity of 1.025 to 1.026 (roughly 35 parts per thousand salinity) for most reef applications. A refractometer is the standard salinity measurement tool.

Substrate and Decor

Freshwater Substrates

Inert substrates like gravel or black sand are suitable for fish-only tanks. For planted tanks, a nutrient-rich substrate like Fluval Stratum, ADA Aqua Soil Amazonia, or UNS Controsoil provides cation exchange capacity that holds fertilizer for plant roots.

Saltwater Substrates

Live sand seeded with beneficial bacteria is standard for marine tanks. CaribSea Arag-Alive is a widely used pre-seeded aragonite sand that also helps buffer alkalinity.

Decorations

Fish need hiding spots to feel secure, regardless of species. Rocks, driftwood, PVC pipes disguised under a substrate, and purpose-built caves all serve this function. Avoid decor with sharp edges, plastic parts that degrade in water, and anything painted that isn't rated aquarium-safe.

For a complete breakdown of the supplies that matter most for each tank type, our Best Aquarium Equipment guide is a good starting resource. For a curated list of what actual hobbyists rate most highly, The Best Aquarium and Pet Supply covers gear across all categories.

FAQ

How much does it cost to set up a basic freshwater aquarium? A complete beginner freshwater setup in a 20-gallon tank with quality (not premium) equipment runs $150 to $250. This includes the tank, a HOB filter, a heater, basic lighting, a thermometer, a test kit, water conditioner, substrate, and decor. Fish are additional, typically $2 to $10 each for common community species.

What fish are easiest for beginners? Guppies, corydoras catfish, neon tetras, mollies, and platies are all genuinely beginner-friendly because they tolerate moderate water conditions, are widely available, and are inexpensive if one doesn't survive the initial acclimation. Avoid bettas in community tanks (males fight), goldfish in tropical tanks (wrong temperature), and any fish labeled "aggressive" until you have experience managing compatibility.

How long does it take to cycle a new aquarium? A new aquarium takes 4 to 8 weeks to fully cycle without intervention. The cycle can be sped to 1 to 2 weeks by adding beneficial bacteria products like Tetra SafeStart Plus or Seachem Stability and starting with a light fish load. Test water weekly during cycling to track ammonia and nitrite levels falling to zero.

Do I need all this equipment before buying fish? Yes. The filter, heater, and cycling period all need to be in place before adding fish. Adding fish to an uncycled tank causes ammonia to spike rapidly and usually results in fish loss within days. Set up and cycle the tank first, then add fish.

Building Your Supply List

Start with the essentials: filter, heater, thermometer, test kit, water conditioner, and substrate. Pick your fish species before buying decor and specialty equipment so you're buying what those specific fish actually need rather than what looks interesting in the pet store. A 20-gallon community tank with quality basics will keep fish healthy and happy indefinitely. Add planted tank supplies, CO2 equipment, or reef-specific gear only when you're ready to move in that direction.