A fish tank needs more than just water and fish. At minimum, you need a filter, heater (for tropical species), lighting, a thermometer, a water conditioner, substrate, and a test kit. Beyond that baseline, there are dozens of optional items that make the hobby easier and more enjoyable.
This guide breaks down the essential fish tank items, what each one does, what to expect to spend, and which optional upgrades are actually worth the money versus which ones you can skip.
The Non-Negotiable Equipment Every Tank Needs
Some items aren't optional. Without these, fish either die quickly or suffer from preventable problems.
Filtration
A filter is the most important item in your tank. It does three jobs: mechanical filtration (trapping debris), biological filtration (growing beneficial bacteria that convert toxic ammonia into safer nitrate), and sometimes chemical filtration (removing dissolved compounds with activated carbon).
For a 20 to 55-gallon tank, the Aqueon QuietFlow 30 or 55 hang-on-back filters are reliable and widely available. For larger tanks, canister filters like the Fluval 307 or Eheim Classic 350 give you more media volume and better flow. A good rule of thumb is to filter the full tank volume 4 to 10 times per hour, so a 40-gallon tank needs a filter rated for at least 160 GPH.
Heating
Most popular fish, including tetras, bettas, guppies, cichlids, and plecos, are tropical and need water between 74 and 80 degrees Fahrenheit. A submersible heater keeps that stable. The Aqueon Pro 50-watt heater is shatterproof and accurate to within one degree. For larger tanks, use two heaters at half the combined wattage rather than one large heater. This provides redundancy if one fails and distributes heat more evenly.
Goldfish and white cloud minnows don't need a heater and do fine at room temperature.
Lighting
Plants need light to photosynthesize. Fish don't technically require light, but a proper light cycle (8 to 10 hours per day, turned off at night) regulates their behavior and keeps algae under control. Most tank hoods include basic LED lighting that works fine for low-light plants like java fern and anubias. If you want to grow demanding plants, upgrade to a Fluval Plant 3.0 or a Current USA Satellite Freshwater LED Plus.
Testing and Water Chemistry Items
You can't tell by looking at water whether ammonia, nitrite, or nitrate levels are dangerous. A test kit is essential, especially during the first 4 to 8 weeks when the tank is cycling.
The API Freshwater Master Test Kit is the standard recommendation. It tests for pH, ammonia, nitrite, and nitrate using liquid reagents that are more accurate than strip tests. One kit lasts about 800 tests, which is roughly 2 to 4 years of regular use for most hobbyists.
A digital thermometer like the Zacro LCD Digital Aquarium Thermometer gives you a constant readout without having to open the tank. Stick-on thermometers are less accurate but better than nothing.
For saltwater tanks, you'll also need a refractometer to measure salinity. The Milwaukee MA887 is accurate to 0.001 specific gravity and costs around $25.
Water Treatment Products
Tap water contains chlorine and chloramine, both of which kill beneficial bacteria and harm fish. A dechlorinator is non-optional. Seachem Prime is the go-to choice for most hobbyists because a single 500ml bottle treats 5,000 gallons and it also detoxifies ammonia temporarily, which is useful during the cycling process.
For new tanks or tanks recovering from illness, Seachem Stability provides a concentrated dose of beneficial bacteria to accelerate biological filtration.
Substrate and Decorations
Substrate serves practical and aesthetic purposes. It provides a surface for beneficial bacteria to colonize and anchors live plants.
Gravel works for most fish. Rinse it thoroughly before use because the dust clouds water for days if you don't. Use 1 pound of gravel per gallon as a rough guide. Sand is better for bottom-dwelling fish like corydoras and kuhli loaches, which like to sift through the substrate naturally. CaribSea Super Naturals Torpedo Beach Sand is popular and safe for most setups.
Decorations matter for fish behavior. Shy species like bettas, oscars, and most cichlids need caves or hiding spots to feel secure. Without them, they spend most of their time hiding in corners and showing stress behavior. Terra cotta pots, PVC pipe, and resin caves all work.
For a complete guide on stocking a tank from scratch, the Best Online Fish Supply Store article covers where to source both equipment and livestock at reasonable prices.
Maintenance Tools
Regular maintenance keeps fish healthy and prevents problems before they start.
Gravel Vacuum
A gravel vacuum removes waste from the substrate during water changes. The Python No Spill Clean and Fill is the gold standard for tanks over 30 gallons because it connects to your faucet and handles draining and refilling without buckets. For smaller tanks, a simple Marina Easy Clean Gravel Cleaner works fine.
Algae Scraper
Algae on the glass is normal and inevitable. A magnetic algae scraper like the Mag-Float lets you clean the interior glass without getting your hands wet. For acrylic tanks, use a scraper specifically labeled safe for acrylic to avoid scratching.
Bucket and Siphon Hose
Dedicate a bucket exclusively to your aquarium. Soap residue from household buckets will harm fish even in trace amounts. A 5-gallon bucket works for most tanks up to 30 gallons. For larger tanks, a 15 or 20-gallon utility bucket or multiple trips with a 5-gallon makes water changes manageable.
Optional Upgrades Worth Considering
Some items aren't necessary at the start but improve the hobby once you're past the basics.
An air pump and air stone increase surface agitation and oxygen levels. This is especially useful in heavily stocked tanks or during power outages. The Tetra Whisper 60 is near-silent and reliable.
A CO2 system is worth investing in if you want to grow demanding aquatic plants. CO2 is the limiting factor for plant growth in most setups, even when lighting and fertilizer are adequate. A complete CO2 setup, tank, regulator, diffuser, and drop checker, costs $80 to $200 for a starter kit like the Aquatek Mini CO2 Regulator bundle.
For fish that need additional aeration or specific oxygen levels, the Best Oxygen Machine for Fish Tank Price guide compares air pumps and aerators at different price points.
What to Buy First vs. What Can Wait
If you're setting up your first tank, buy in this order: tank, filter, heater, substrate, dechlorinator, test kit, thermometer. Get those established and let the tank cycle before adding fish. Most of the rest can come later as you figure out what your specific setup needs.
Don't buy fish the same day as the tank. The nitrogen cycle takes 4 to 8 weeks, and adding fish before it's complete leads to ammonia poisoning, which is the number one cause of fish death in new setups.
FAQ
How much does it cost to set up a basic fish tank? A 20-gallon starter setup with a filter, heater, basic lighting, substrate, decor, and starter chemicals typically runs $80 to $150. Upgrading to a 55-gallon with a canister filter and nicer lighting can push that to $300 or more before livestock.
Do I need a protein skimmer for a freshwater tank? No. Protein skimmers are for saltwater/reef tanks. In freshwater, they're not effective or necessary. Your biological filter handles the work a skimmer does in saltwater.
Can fish survive without a heater? Cold-water species like goldfish and hillstream loaches don't need one, as long as your room stays between 65 and 72 degrees Fahrenheit. But most tropical fish will become lethargic, stop eating, and become disease-prone below 72 degrees.
What's the most commonly forgotten item when setting up a tank? A water conditioner. People buy tanks, filters, and fish, then add straight tap water without treating it. Chlorine and chloramine in municipal water will damage fish gills and kill off beneficial bacteria. Always treat tap water before it enters the tank.
The Bottom Line
The core fish tank items are less complicated than they seem once you understand what each one does. Start with filtration, temperature control, and water chemistry management, and build from there. The maintenance tools and optional upgrades make the hobby more enjoyable over time, but a simple, consistent setup with the basics in place will keep fish healthy for years.