Setting up a fish tank requires more than just a glass box and water. The core supplies every tank needs are a filter, a heater (for tropical fish), a light, a substrate, a water conditioner, and a test kit. That's the honest short list. Everything else is either niche-specific or nice to have once you're established. If you're starting out or restocking your setup, this guide walks through each category with specific product recommendations and the numbers that matter.
We'll cover the essential equipment categories, what to spend money on vs. What to skip, the difference between freshwater and saltwater supply needs, and where to find good deals without sacrificing quality.
The Non-Negotiables: Core Equipment Every Tank Needs
Every fish tank, regardless of size or type, needs filtration, lighting, and a way to maintain water quality. Here's what each piece actually does.
Filtration
The filter is the most important piece of equipment in your tank. It runs 24/7 and handles three types of filtration: mechanical (removing particles), biological (beneficial bacteria breaking down ammonia), and chemical (activated carbon or other media absorbing toxins).
For beginners, a hang-on-back (HOB) filter is the most practical choice. The Aquaclear 30 handles tanks up to 30 gallons, the Aquaclear 50 handles up to 50 gallons, and they've been the go-to recommendation in the hobby for decades because they're reliable, easy to clean, and the media is customizable. A 30-gallon setup with an Aquaclear 30 will run you about $35-40.
Canister filters like the Fluval 207 or Eheim Classic 250 are better for 40+ gallon tanks or any setup where you want stronger biological filtration with less weekly maintenance. The tradeoff is higher upfront cost ($80-150) and more complex setup.
Sponge filters work well in tanks under 20 gallons, especially breeding setups or tanks with small fry, because they can't suck up small fish. They're cheap ($5-15) and nearly indestructible.
Heaters
Tropical fish need water between 74-80°F. Without a heater in a home that cools to 65°F in winter, your fish will get sluggish, stop eating, and eventually die. The Aqueon Pro 50W handles tanks up to 15 gallons. The Eheim Jager 150W is the go-to for 30-50 gallon tanks. Both have dual-walled glass or quartz construction and auto-shutoff when water drops below a set level.
Size your heater at 3-5 watts per gallon. A 40-gallon tank needs 120-200 watts, so a 150W heater is appropriate.
Coldwater fish (goldfish, axolotls) don't need a heater, but they may need a chiller if your home gets warm in summer.
Lighting
Fish need a natural day/night cycle, which means 8-10 hours of light per day. For fish-only tanks, basic LED fixtures are fine. The Fluval Aquasky 2.0 and Nicrew ClassicLED are popular budget options that provide good color rendering at $20-50 for a 24-inch fixture.
Planted tanks need more intensity and the right spectrum. Full-spectrum LEDs in the 6500K range at high PAR values support plant growth. The Finnex Planted+ 24/7 and Fluval Plant 3.0 are both well-regarded for planted setups.
Water Chemistry and Testing Supplies
You can't see ammonia in water. You can't smell nitrite. These compounds build up silently and kill fish before you notice anything wrong. A basic test kit is not optional.
The API Freshwater Master Test Kit is the industry standard. It tests pH, ammonia, nitrite, and nitrate and costs around $25-30. Unlike test strips, it uses liquid reagents that give accurate readings even at low concentrations. Test strips are cheaper but notorious for giving false negatives in the 0.25-0.5 ppm ammonia range, which is exactly where problems start.
Water conditioner removes chlorine and chloramines from tap water. Seachem Prime is the most popular because 1 mL treats 10 gallons, a single 100mL bottle ($7) lasts months, and it also temporarily detoxifies ammonia and nitrite during cycling.
Aquarium salt is sometimes recommended for freshwater tanks, though it's controversial. Some species (mollies, platies, certain livebearers) tolerate or prefer a small amount. Goldfish can benefit from it during illness. Most tropical community tanks don't need it.
For saltwater tanks, you'll also need a refractometer or electronic salinity meter to measure specific gravity. The Milwaukee MA887 refractometer runs about $30 and is accurate enough for reef keeping.
For more options on where to source these products, check out the best online fish supply store guide, which compares pricing and selection across major retailers.
Substrate and Decorations
Substrate isn't just decorative. It provides surface area for beneficial bacteria, anchors plants, and affects water chemistry in some cases.
Gravel is the most common choice. Standard aquarium gravel like Carib Sea Super Naturals comes in multiple colors and sizes. Larger gravel (3-5mm) traps debris, so you'll need to vacuum more often. Finer sand (1-2mm) looks more natural but can go anaerobic in thick layers.
Planted substrate like Fluval Stratum or ADA Aqua Soil is designed for planted tanks. It's nutrient-rich and slightly acidic, which suits most aquatic plants and soft-water fish. It costs more ($15-30 for a small bag) but makes a real difference in plant growth.
Decorations provide hiding spots that reduce fish stress. Caves, driftwood, and dense plant clusters allow timid fish like plecos, cory catfish, and cichlids to retreat and establish territories. A tank with no hiding spots produces visibly stressed fish that spend most of their time hiding at the back anyway, just without the cover they need.
Avoid painted or metallic decorations in aquariums. Paints can leach into water. Anything labeled "aquarium safe" or made from resin or natural materials (driftwood, rock) is your best bet.
Aeration and Oxygen Equipment
Most tanks with a functioning filter have adequate oxygenation from surface agitation. But high-stocking densities, warm water (which holds less oxygen), heavily planted tanks at night, and species with high oxygen demands all benefit from additional aeration.
Air pumps with airstones are the simplest solution. The Tetra Whisper Air Pump produces strong airflow with minimal noise. A standard bubble wand or airstone runs $2-5 and the pump itself costs $10-20 depending on tank size. You'll need airline tubing and a check valve to prevent back-siphon.
For tanks where oxygen is a real concern, look at the oxygen machine for fish tank price guide, which covers air pumps and diffusers across different tank sizes and oxygen demands.
Cleaning and Maintenance Supplies
Regular maintenance keeps water quality stable and extends the life of all your equipment. The basic kit:
Gravel vacuum/siphon: The Python No Spill Clean & Fill hooks to a faucet and lets you do water changes without carrying buckets. For smaller tanks, a basic hand siphon runs $5-10. For tanks over 40 gallons, the Python or a similar faucet attachment saves enormous time.
Algae scraper: Magnetic algae cleaners like the Mag-Float let you clean the glass without putting your arm in the tank. They cost $10-20 and work on both glass and acrylic.
Bucket: A dedicated 5-gallon bucket for aquarium use only. Never use a bucket that has had soap or cleaning chemicals in it. Soap residue is toxic to fish even in trace amounts.
Net: A basic fish net for moving fish during water changes or tank cleanups. Keep a few sizes, since small fish can slip through large nets.
A well-maintained tank requires about 20-25% water changes every 1-2 weeks depending on stocking density. Heavily stocked tanks may need weekly changes.
The Difference Between Freshwater and Saltwater Supply Lists
Setting up a saltwater or reef tank requires several additional pieces of equipment that freshwater tanks don't need.
Protein skimmer: Removes dissolved organic compounds from water before they break down. Essential for marine tanks with fish over 20 gallons. The AquaMaxx WS-1 handles tanks up to 75 gallons and costs around $80-100.
Powerheads/wavemakers: Coral and many marine fish need strong water movement. Circulation pumps like the Jebao SLW-10 or Hydor Koralia 1150 create the flow that keeps detritus suspended for the filter to remove.
Live rock: The biological backbone of a reef. It houses the beneficial bacteria and provides structural habitat. You need 1-1.5 pounds per gallon as a baseline.
RO/DI water system: Tap water contains silicates, phosphates, and other compounds that fuel algae growth in reef tanks. A reverse osmosis/deionization system produces near-pure water for making saltwater. The standard unit for home use produces 50-100 gallons per day.
Saltwater mix: A quality reef salt like Instant Ocean Reef Crystals or Red Sea Coral Pro Salt blended with RO/DI water to target specific gravity of 1.025-1.026.
The supply list for a reef tank is roughly 3-4x the cost of a freshwater setup, but the livestock is often far more valuable, which justifies the investment.
FAQ
What supplies do I need for a 10-gallon fish tank starter setup?
For a basic 10-gallon freshwater tank you need: a small HOB filter (Aquaclear 20 or Fluval C2), a 50W heater for tropical fish, an LED light, aquarium gravel or sand, a water conditioner (Seachem Prime), a test kit (API Master Test Kit), and a small net and bucket for maintenance. Total cost for quality equipment runs $80-130 depending on where you shop and whether you find sales.
Can I use tap water directly in my fish tank?
No, not directly. Tap water contains chlorine or chloramine added by municipal water treatment, both of which are toxic to fish and will kill beneficial bacteria. Add a water conditioner like Seachem Prime immediately before adding water to the tank. It neutralizes these compounds within seconds.
How often do I need to replace filter media?
It depends on the type. Activated carbon exhausts in 2-4 weeks and should be replaced on that schedule (or skipped entirely, since most tanks don't need chemical filtration long-term). Biological media (ceramic rings, bio balls, sponge) should NEVER be replaced all at once, since it houses your beneficial bacteria colony. Rinse it in old tank water during water changes and replace only 25% at a time if it deteriorates.
What's the minimum tank size for a beginner?
I generally recommend 20 gallons as the starting point, not 5 or 10. Smaller tanks are actually harder to maintain because water parameters swing more dramatically. A small ammonia spike in a 5-gallon tank can reach lethal levels in hours. In a 20-gallon tank, the same amount of ammonia is diluted to a safer concentration while you catch it. Nano tanks under 10 gallons work, but they require more experience and more frequent monitoring.
Key Takeaways
Start with the non-negotiables: a properly sized filter, a heater matched to your fish's needs, a basic LED light, a reliable test kit, and water conditioner. Get those right and your tank will stay stable. Add substrate, decorations, and aeration based on what you're keeping. Saltwater tanks require protein skimmers, live rock, and RO/DI water on top of the basics. Every piece of equipment has a specific job, so buy quality where it counts (filter, heater, test kit) and save money on decorations and accessories.