A freshwater fish tank needs six core categories of supplies to function: a tank, a filter, a heater (for most fish), lighting, a water conditioner, and a test kit. Everything else, the decorations, specialized substrates, CO2 systems, and advanced filtration add-ons, depends on what fish you're keeping and what goals you have for the tank. If you're starting out, buy the essentials first and add to the setup based on what your fish and plants actually need.

This guide covers every supply category for freshwater tanks, what specific products to look at in each category, what you can skip, and how to think about building out your setup without wasting money on equipment you won't actually use.

The Tank: Sizing and Material Choices

Tank size is the single decision that shapes everything else. Larger tanks are genuinely easier to maintain because water chemistry changes more slowly in higher volumes. A 20-gallon tank forgives beginner mistakes. A 5-gallon tank punishes them.

The general rule for stocking: one inch of adult fish body length per gallon, but this understates the needs of fish that produce a lot of waste (goldfish, large cichlids) and overstates the needs of small schooling fish. Research the specific fish you want before deciding on tank size.

Standard beginner sizes: 10-gallon (great for bettas, small community fish), 20-gallon long (most versatile beginner tank), 29-gallon (fits most community fish setups).

Glass tanks are the standard choice: Aqueon, Marineland, and Tetra all produce quality glass tanks. Acrylic tanks are lighter and resist cracking better but scratch more easily and cost more. For most freshwater setups, glass is the right call.

Tank kits that include a light and filter can be a good starting point. The Aqueon 20-Gallon LED Kit, the Tetra 20-Gallon Aquarium Kit, and the Marineland Portrait 5-Gallon are popular and provide most of what you need to get started.

Filtration: The Heart of the System

A filter performs three functions: mechanical filtration (removing solid debris), chemical filtration (removing dissolved organics), and biological filtration (housing beneficial bacteria that process ammonia and nitrite). A good filter addresses all three.

Hang-On-Back (HOB) Filters

HOB filters are the standard choice for tanks up to 55 gallons. They're easy to maintain, reliably available, and effective. The AquaClear 20, 30, 50, and 70 are the most recommended HOB filters in the hobby. They use replaceable foam, activated carbon, and ceramic bio-rings, and the flow rate is adjustable. The Seachem Tidal 35 and 55 are also strong performers with self-priming capability.

Avoid filters with proprietary cartridge systems that must be replaced every 2-4 weeks (like the basic Aqueon QuietFlow cartridges). These are more expensive to maintain and the mandatory cartridge replacement disrupts your beneficial bacteria colony.

Canister Filters

Canister filters work well for tanks 40 gallons and up, for tanks where aesthetics matter (the hardware is hidden below the tank), and for heavily stocked tanks that need high-volume filtration. The Fluval 207, 307, and 407 are the most popular freshwater canister filters. Eheim's Classic and Professionel lines have decades of reliability behind them. Expect to spend $80-150+ on a quality canister filter.

Sponge Filters

Sponge filters powered by an air pump are ideal for breeding tanks, fry tanks, quarantine tanks, and betta tanks where flow needs to be very gentle. The Hikari Bacto-Surge and Aquaneat Bio Sponge filters are inexpensive and reliable. You'll need an air pump (Tetra Whisper 10, 20, or 40) and airline tubing to run them.

Heaters: Non-Negotiable for Most Fish

Almost all tropical freshwater fish need water temperatures between 72 and 82°F. Room temperature in a typical home (68-72°F) is too cold for tetras, livebearers, bettas, cichlids, rainbowfish, and most other commonly kept species.

The heater sizing formula: 3-5 watts per gallon for most tanks. A 20-gallon tank needs a 75-100W heater. A 55-gallon tank needs a 150-200W heater.

Specific recommendations: - 5-10 gallons: Aqueon Pro 25W, Cobalt Aquatics Neo-Therm 25W - 10-29 gallons: Eheim Jager 50W or 75W, Cobalt Neo-Therm 50W - 30-55 gallons: Eheim Jager 100W or 125W, Fluval E-Series 100W - 55+ gallons: Eheim Jager 200W, or dual heaters for redundancy

The Eheim Jager has a recalibrate feature, a glass construction that resists cracking, and an excellent accuracy record. The Cobalt Neo-Therm has a flat profile that's less visible in the tank and holds temperature within 0.5°F. Both are worth the price premium over cheap generic heaters, which have a documented tendency to fail dangerously.

Don't skip a separate aquarium thermometer. Heater dials are not always accurate, and you need to verify actual water temperature after installation.

Lighting: Match the Light to the Plants

For fish-only tanks, almost any LED light provides adequate light for viewing fish and keeping the tank visually appealing. For planted tanks, light intensity matters a great deal.

Fish-only and low-light planted tanks: Aqueon LED strip lights, Nicrew ClassicLED, Fluval Aqua Sky LED. These run $20-50 and work well for Anubias, Java fern, Cryptocoryne, and moss.

Medium-light planted tanks: Nicrew ClassicLED Plus, Hygger 957 Full Spectrum, Fluval Plant 3.0. These provide PAR values in the 50-100 range at typical tank depths. Suitable for Amazon swords, stem plants, and most common aquarium plants.

High-light planted tanks: Fluval Plant 3.0 on higher settings, Chihiros RGB series, Finnex Planted+. For carpet plants, demanding stem plants, and tanks with CO2 injection.

Run your light 8-10 hours per day on a timer. More than 12 hours promotes algae. Less than 6 hours limits plant growth and makes the tank look dim.

See our best online fish supply store guide for current pricing on lighting options across these categories.

Substrate: What Goes on the Bottom

The substrate you choose affects both aesthetics and plant health. For fish-only tanks, almost anything works. For planted tanks, substrate composition matters.

Inert substrates (gravel, sand): Pool filter sand, CaribSea Super Naturals, and similar products are inert and don't affect water chemistry. They support plants with root tabs added (like Seachem Flourish Tabs) but don't provide nutrition on their own.

Enriched substrates (planted tank substrates): Fluval Stratum, ADA Aqua Soil, CaribSea Eco-Complete, and Seachem Flourite provide nutrients that aquarium plants can use through their roots. These substrates are a significant upgrade for planted tanks and eliminate the need for root tabs for the first 12-18 months.

Substrate depth: 2-3 inches is sufficient for most setups. Planted tanks with root-feeding plants (Swords, Crypts) benefit from 3-4 inches of substrate.

Water Conditioner and Chemistry Supplies

Dechlorinator: Non-negotiable. Chlorine and chloramine in tap water kill fish and beneficial bacteria. Seachem Prime is the standard choice because it also detoxifies ammonia and nitrite at double dose. API Stress Coat is a solid alternative that also adds a slime coat protectant.

Test kit: The API Freshwater Master Test Kit is the standard for freshwater tanks. It tests ammonia, nitrite, nitrate, and pH. Avoid strip tests, which are unreliable. The liquid test kit is accurate enough to use as your primary monitoring tool.

Beneficial bacteria starter: Seachem Stability, Tetra SafeStart Plus, and Fritz Turbo Start 700 all help establish the nitrogen cycle in new tanks. None of these eliminate the cycle, but they accelerate it from 4-6 weeks to potentially 2-3 weeks.

Maintenance Tools: The Unglamorous Essentials

Gravel vacuum/siphon: A Python No Spill Clean and Fill (for larger tanks) or a basic Lee's Economy Gravel Vacuum allows you to remove detritus from the substrate during water changes without draining the whole tank. This is one of the most-used tools in freshwater fishkeeping.

Algae scraper: A magnetic algae cleaner (Flipper Float or Mag-Float) lets you scrub algae from the glass without getting your arm wet during every cleaning session.

Fish net: At least one net for moving fish, removing sick fish for treatment, or catching escapees. Multiple sizes are useful if you keep both large and small fish.

Bucket (dedicated, never used for soap or cleaning products): For mixing dechlorinated water before adding to the tank.

For aeration equipment if your filter doesn't provide enough surface agitation, see our best oxygen machine for fish tank price guide.

FAQ

What supplies do I need to set up a freshwater fish tank for the first time?

The essentials are: tank, filter (sized for your tank volume), heater (if keeping tropical fish), light, gravel or substrate, water conditioner, and a test kit. For stocking, add fish food appropriate for your species. Optional but useful: a thermometer, gravel vacuum, algae scraper, and a beneficial bacteria starter culture. Everything else depends on your specific setup goals.

How much does it cost to set up a freshwater tank?

A basic 20-gallon community tank setup with quality equipment (Aqueon tank kit, AquaClear 30 filter, Eheim Jager 75W heater, API test kit, substrate, and decorations) runs approximately $150-200. Upgrading to a planted tank with a quality light, enriched substrate, and CO2 system adds another $100-200.

Do I need a CO2 system for a freshwater planted tank?

Not always. Plants that tolerate low light, like Anubias, Java fern, Cryptocoryne, and mosses, grow fine without CO2 injection when given adequate light and regular fertilizer. CO2 injection becomes beneficial for medium-to-high-light plants, carpet plants, and any setup where you want noticeably faster, lusher plant growth.

How often do I need to do water changes?

For a properly cycled tank with a functioning filter and moderate fish load, weekly water changes of 20-25% maintain water quality effectively. Tanks with higher bioloads (goldfish, heavily stocked tanks, large fish) may need more frequent or larger changes. Test your water weekly until you understand your tank's specific nitrogen cycle rhythm.

Building Your Supply List Smartly

Start with the core six: tank, filter, heater, light, water conditioner, test kit. Get those right before adding anything else. Then add based on what your fish and plants actually need, not what looks appealing in the pet store. A good canister filter and quality heater will serve you better than spending that money on decorations and supplements your tank doesn't need.