Setting up a fish tank requires more than just the tank itself. The accessories that work alongside the tank, from filtration to heating to substrate, are what actually determine whether your fish thrive or struggle. A tank with no accessories is just an expensive glass box. The good news is that a basic, fully functional setup for a 20-gallon freshwater tank can cost less than $150, including the tank, filter, heater, light, substrate, and conditioner.
Whether you're setting up your first aquarium or upgrading an established one, this guide covers every accessory category you'll encounter. I'll explain what each piece of equipment does, which products are worth the money, and how to prioritize your purchases so you're not spending money on things you don't need yet.
The Tank Itself: What to Look For
Glass tanks are heavier but more scratch-resistant than acrylic. Acrylic is lighter, clearer, and better for unusual shapes, but scratches easily and requires special cleaning tools. For most beginners, glass is the practical choice.
Starter kits bundle the tank with basic accessories and often represent good value. The Aqueon Aquarium Starter Kit 20 includes a tank, filter, heater, thermometer, and hood for around $100 to $130. The Marineland 10-Gallon Biowheel LED Aquarium Kit is a popular smaller option. The tradeoff with kits is that the included accessories are usually entry-level, meaning you may upgrade the filter or heater within a year or two.
Buying the tank and accessories separately gives you more control over quality at each component level. This makes sense for tank sizes above 40 gallons, where the quality difference between kit components and standalone equipment becomes more significant.
Regardless of tank size, think about placement before buying. Aquariums should not go near windows (algae growth from sunlight), vents (temperature fluctuations), or in high-traffic areas where people regularly bump into them. They also need a dedicated stand rated for the weight. A 55-gallon tank filled with water, gravel, and decor weighs over 600 pounds.
Essential Accessories for Any Fish Tank
Filtration
Filtration is the most important accessory. The filter processes waste through mechanical filtration (removing particles), biological filtration (beneficial bacteria converting ammonia to less harmful compounds), and optionally chemical filtration (activated carbon removing discoloration and odors).
The Aqueon QuietFlow 30 handles tanks up to 30 gallons and has self-priming. The AquaClear 50 is a highly regarded HOB filter for tanks up to 50 gallons, known for its adjustable flow rate and customizable media basket. For larger tanks, the Fluval 307 canister filter handles up to 70 gallons and runs very quietly.
Match your filter to your stocking level, not just your tank size. A lightly stocked 40-gallon tank does fine with a filter rated for 40 gallons. A heavily stocked 40-gallon tank needs a filter rated for 60 to 80 gallons.
Heaters
Tropical freshwater fish, which includes most popular species like tetras, gouramis, livebearers, and cichlids, need water temperatures between 74 and 80 degrees Fahrenheit. The Eheim Jager is one of the most reliable heaters available at any price point. The Fluval E-Series offers a digital readout of both target and actual temperature. Submersible heaters should be placed horizontally near the filter output for even heat distribution.
Thermometers
Never trust a heater's built-in thermostat alone. A separate thermometer placed on the opposite side of the tank from the heater confirms actual water temperature. LCD stick-on thermometers are cheap but less accurate. Digital probe thermometers give readings to the decimal and cost about $10 to $15.
Lighting
A photoperiod of 8 to 10 hours per day keeps fish on a natural rhythm. Longer periods encourage algae. LED fixtures are now standard because they run cool, last years, and often include timers or dimmers. For basic fish tanks, any LED fixture in the 5,500 to 7,000 Kelvin range provides natural-looking light. For planted tanks, the Fluval Plant 3.0 or the Finnex Planted+ 24/7 are current standards.
Substrate, Decor, and Hardscape
Your substrate choice sets the look of the tank and affects certain fish species that sift or burrow. Fine sand like CaribSea Super Naturals or Carib Sea Torpedo Beach Sand works for species like corydoras, loaches, and sand-dwelling cichlids. Standard aquarium gravel in 2 to 5mm sizes works for most community fish and planted tank setups.
Hiding Spots and Plants
Fish need places to retreat. Without cover, they become chronically stressed, which suppresses immune function and leads to disease. Live plants, driftwood, rock formations, and aquarium-safe ceramic decorations all count as cover. Even a simple arrangement of a few pieces of driftwood and a rock or two dramatically improves fish behavior and color.
For planted tanks, check our best freshwater aquarium accessories guide for CO2 systems, plant fertilizers, and specialized lighting that support plant growth.
Maintenance Accessories You'll Use Every Week
Once the tank is running, you'll need tools for ongoing maintenance.
A gravel vacuum is non-negotiable. The Python No Spill Clean and Fill is the best option for tanks over 40 gallons because it connects to your faucet and eliminates bucket hauling. For smaller tanks, the API Gravel Tube Cleaner or a similar hand-pump siphon works fine.
A magnetic algae cleaner like the Flipper Premium makes glass cleaning easy without putting your hands in the tank. Keep a dedicated bucket for aquarium use only. Soap residue in a bucket that's been used for other things can poison fish.
Water conditioner is needed for every water change. Seachem Prime is the standard recommendation. It neutralizes chlorine, chloramines, and temporarily detoxifies ammonia.
A test kit like the API Master Test Kit covers ammonia, nitrite, nitrate, and pH. Running tests once a week for the first two months of a new tank tells you whether your nitrogen cycle has established and whether your maintenance routine is working.
Upgrading Your Accessories Over Time
The most common upgrade path looks like this:
- Start with a basic filter and heater from a kit.
- Replace the filter first if the kit filter is undersized or noisy.
- Add a second heater for redundancy if the tank is a reef or expensive fish collection.
- Upgrade lighting if you add live plants.
- Add an auto top-off unit if evaporation requires daily attention.
- Consider a CO2 system if planted tank growth is slow.
There's no need to buy premium versions of everything on day one. A Fluval 307 canister filter on a new tank with no fish in it does the same thing as a basic HOB. Upgrade when the upgrade solves an actual problem.
See our buy aquarium accessories online guide for current pricing from major retailers and what to look for during seasonal sales.
FAQ
What's the minimum I need to buy to set up a fish tank properly? Tank, filter, heater (for tropical fish), thermometer, light, substrate, water conditioner, and a test kit. Decorations are optional but important for fish welfare. That's the core list.
How long do I need to wait before adding fish to a new tank? The nitrogen cycle takes two to six weeks to complete. You can speed this up by adding bottled beneficial bacteria like Tetra SafeStart Plus or Seachem Stability. Test ammonia, nitrite, and nitrate regularly during this period. Only add fish once ammonia and nitrite read zero.
How many gallons per hour should my filter be? Aim for a turnover rate of 4 to 6 times your tank volume per hour. A 30-gallon tank needs a filter pushing 120 to 180 gallons per hour minimum. Cichlid and goldfish tanks, which produce more waste, benefit from the higher end of that range.
Do I need a lid on my fish tank? Yes for almost all fish. Many species jump, especially when startled. A lid also reduces evaporation and keeps cats and other pets from reaching into the tank. Glass canopy lids are better than plastic ones because they're more durable and allow more light through.
Where to Start
If you're setting up from scratch, buy the tank, filter, and heater first. Get those running and cycling before you spend on decoration. Then add substrate, hardscape, and decor before the fish arrive. Running the tank for two to four weeks before adding livestock gives your filter time to establish beneficial bacteria and gives you time to verify equipment is working correctly. That patience up front prevents a lot of early problems.