Pet fish accessories cover a wide range, from essential equipment your fish genuinely need to survive, to decorative items that serve aesthetic purposes only. If you're setting up a new tank or upgrading an existing one, the short answer is this: prioritize filtration, a heater (if you're keeping tropical fish), a thermometer, and a water conditioner. Everything else is either optional or category-specific depending on your fish.
This guide breaks down the must-haves versus the nice-to-haves, covers the main product categories with specific recommendations, and helps you figure out what actually makes sense for your setup rather than buying everything at once.
Essential Accessories Every Fish Tank Needs
Some accessories aren't optional. Without these, fish health deteriorates quickly regardless of tank size or species.
Filtration
The filter is the single most important piece of equipment in any aquarium. It removes waste, cycles beneficial bacteria, and keeps ammonia and nitrite at safe levels. For most freshwater community tanks, a hang-on-back (HOB) filter is the easiest starting point.
The Aquaclear 20 is a strong choice for tanks up to 20 gallons. It runs around $30 to $40 and uses a three-stage filtration media tray you can customize with different sponge, carbon, and biological media. For larger tanks, the Aquaclear 70 handles up to 70 gallons and costs $50 to $65.
Canister filters like the Fluval 307 or the Sunsun HW-304B offer more filtration volume and quieter operation, but they're more expensive and take longer to set up. They're generally worth the investment for tanks 55 gallons and up, or for fish that produce heavy waste, like goldfish and cichlids.
Water Conditioner
Tap water contains chlorine and chloramines that kill fish and destroy beneficial bacteria. Water conditioner neutralizes these instantly. Seachem Prime is the most cost-effective option. A 500 mL bottle treats up to 5,000 gallons and costs around $12 to $15. It also detoxifies ammonia and nitrite in small amounts, which provides a buffer during the nitrogen cycle.
Thermometer
You need to know the actual temperature of your tank, not just what the heater is set to. Cheap stick-on strip thermometers are inaccurate by 2 to 4 degrees. Digital thermometers with a probe, like the Zacro LCD Digital Aquarium Thermometer, give accurate readings to within 1 degree and cost under $10.
Heating and Temperature Control
Tropical fish require water temperatures between 74 and 80 degrees Fahrenheit. A heater is mandatory for species like betta fish, tetras, guppies, discus, and most cichlids.
Choosing a Heater
The standard rule is 3 to 5 watts per gallon. For a 20-gallon tank, a 75-watt heater is sufficient. For a 50-gallon tank, a 150 to 200-watt heater works well.
The Aqueon Pro 100W Heater has a fully submersible design and shatterproof plastic housing, making it safer around active fish. It costs around $25 to $35. For high-end precision, the Inkbird IBS-M2 digital controller paired with a dumb heater lets you set a specific temperature and have the controller do all the switching, preventing the temperature swings that cheaper heaters can produce.
Coldwater fish like goldfish and white cloud mountain minnows don't need a heater if your room stays above 65 degrees Fahrenheit, but they do need good filtration and a thermometer to monitor seasonal changes.
Lighting Accessories
Light serves two purposes: it lets you see your fish, and it supports plant growth if you're keeping live plants.
Basic LED Lighting
Most modern aquariums come with LED light bars that are adequate for viewing and for low-light plants like java fern, anubias, and java moss. Brands like Nicrew and Hygger make budget LED lights in the $15 to $30 range that work well for non-planted or low-tech planted setups.
Planted Tank Lighting
For medium or high-light plants (carpeting plants, stem plants, red plants), you need a more powerful light. The Fluval Plant 3.0 and the Chihiros WRGB II are popular choices among planted tank keepers. They run $80 to $150 but produce the full spectrum that plants need for dense, healthy growth.
You can browse a full selection of lighting options along with other core equipment in our guide to Best Freshwater Aquarium Accessories.
Decorations and Substrate
Decorations are optional for fish health, but fish do benefit from having places to hide. Stress from open, exposed tanks shortens fish lifespans and suppresses breeding behavior.
Substrate
Gravel or sand serves as more than decoration. It anchors plants, houses beneficial bacteria, and affects water chemistry. Soft substrates like CaribSea Super Naturals or API Freshwater Sand are better for bottom-dwelling fish like corydoras and loaches, which can injure their barbels on coarse gravel.
Planted tank substrates like Fluval Stratum or ADA Aqua Soil contain nutrients that feed plant roots and are worth using if you're serious about growing plants. They cost more, typically $20 to $50 per bag, but they make a real difference in plant health compared to inert gravel.
Rocks, Driftwood, and Hides
Smooth river rocks, aquarium-safe resin caves, and driftwood give fish territory and hiding spots that reduce aggression and stress. Malaysian driftwood releases tannins that slightly acidify the water, which benefits species like betta fish and most tetras. If you don't want the tannin tint, boil the driftwood for several hours or soak it for a few weeks before adding it to the tank.
Maintenance Accessories
Regular maintenance is the difference between a healthy tank and a problem tank. A few inexpensive tools make this much easier.
Gravel Vacuum
A siphon gravel vacuum removes debris and waste from the substrate during water changes. The Python No Spill Clean and Fill system is the most convenient option if your tank is near a sink. It connects directly to a faucet and lets you siphon water out and then refill without carrying buckets. The starter kit runs around $35 to $50.
For smaller tanks, a simple hand-pump siphon from Lee's Aquarium costs $8 to $12 and does the job effectively.
Algae Scraper
Algae grows on glass surfaces in any lit aquarium. A long-handled scraper with a magnetic outer pad lets you clean the inside glass without getting your arm wet. The Fluval Long Reach Algae Cleaner and the Mag-Float Glass Cleaner are both reliable choices in the $10 to $25 range.
Test Kit
Weekly water testing catches problems before they harm fish. The API Freshwater Master Test Kit tests pH, ammonia, nitrite, and nitrate and costs around $20 to $30. It includes 800+ tests, making it far more cost-effective than individual test strips.
If you want to compare prices and shop for multiple accessories at once, checking out options at Buy Aquarium Accessories Online lets you compare products across multiple retailers without visiting multiple stores.
FAQ
What accessories do I need for a betta fish specifically? Betta fish need a tank of at least 5 gallons (10 gallons is better), a gentle filter that doesn't create strong flow, a heater set to 78 degrees Fahrenheit, and a lid since bettas jump. They also benefit from silk or live plants and at least one hide. Avoid anything with sharp plastic fins that can shred their long tails.
Do fish need accessories like bubblers and decorations to be healthy? A bubbler (air pump with airstone) adds oxygen and helps in tanks with low surface agitation, but it's not universally required if your filter creates enough surface movement. Decorations are optional from a health standpoint, but hides reduce stress in most fish. Some fish, like cichlids, genuinely need territory markers to thrive.
How often should I replace aquarium accessories? Filter media sponges last 6 months to several years with regular rinsing. Carbon media needs replacing every 4 to 6 weeks. Heaters typically last 2 to 5 years. Thermometers and air pumps vary, but diaphragm air pumps usually need a diaphragm replacement or full replacement after 1 to 3 years.
What's the minimum setup for a 10-gallon fish tank? A 10-gallon tank needs a filter rated for at least 10 gallons (an Aquaclear 20 works well), a heater if keeping tropical fish (a 50-watt heater is appropriate), a thermometer, a lid, and a water conditioner. Substrate, lighting, and decorations are additional but make the tank easier to maintain and better for fish wellbeing.
What to Prioritize
Build your setup from the inside out: start with the filter, heater, and water conditioner, then add a thermometer and test kit, and finally address aesthetics and maintenance tools. Spending $100 to $150 on core equipment for a 20-gallon tank is realistic and gives you everything needed for long-term success. Decorations and extras can be added gradually as you learn what your particular fish need.