Aquarium Light Guide India: LED, Hours & Setup

Choose an aquarium light by matching it to your tank: a basic LED is enough for a fish-only tank, while a planted tank needs a higher-output, full-spectrum LED. Run it for 6–8 hours a day on a timer, never 24/7. The right light keeps fish colours vivid, lets live plants thrive, and shows your aquarium at its best, the wrong light, or too many hours, fuels algae. This guide explains every type of aquarium light, how much light and how many hours your tank needs, spectrum and colour, algae control, and how to size a light for your tank, written for fishkeepers in India.

Lighting is the most misunderstood part of the aquarium. Too little and plants die and fish look dull; too much and algae takes over. Get it right and everything else becomes easier. Here is how.

What does an aquarium light actually do?

An aquarium light serves three jobs, and which one matters most depends on your tank:

• It powers live plants. Plants need light to photosynthesise. In a planted tank, light is effectively “food”, intensity and spectrum directly control growth.
• It shows off your fish and tank. Good lighting brings out the natural colours of your fish and hardscape, the single biggest visual upgrade you can make.
• It sets the day/night rhythm. A consistent photoperiod gives fish a stable routine and keeps plants on a healthy cycle.

A fish-only tank needs light mainly for viewing; a planted tank needs light as a growth engine. That single distinction drives almost every buying decision below.

Do you even need an aquarium light?

For most tanks, yes, but for different reasons. A fish-only tank can technically survive on ambient room light, but a proper light makes the fish look far better and sets a day/night cycle; just avoid placing the tank in direct sunlight, which causes algae. A planted tank cannot survive without adequate light, the plants will melt and die. So the question is not really “do I need a light” but “how much light do I need,” which depends entirely on whether you keep plants. See do aquarium fish need light for the full answer.

Types of aquarium lights

Almost all modern aquarium lights are LED, they are energy-efficient, run cool, last for years and come in every form factor. The main types you will see in India:

For a planted aquascape, a flat-panel or bracket full-spectrum LED is the standard; for a betta or nano tank, a small clip-on is perfect. A submersible tube is the budget option and doubles as dramatic back-lighting.

How much light does your tank need?

Light requirement scales with your goal, not just tank size. The simplest way to think about it is in three tiers:

A common beginner mistake is buying a powerful planted-tank light for a fish-only tank, it just grows algae. Match the light to the plants you actually keep. For the full planted breakdown, see best lighting for a planted aquarium.

How many hours should the light be on?

This is the question that decides whether you get a beautiful tank or an algae farm. The short answer: 6–8 hours a day for most tanks, run on a timer for consistency. Fish-only tanks can sit at the lower end; planted tanks usually need 7–8 hours; high-tech tanks may push to 8–10 with CO2. More light is not better, beyond your plants’ needs, extra hours simply feed algae. The full schedule, including siesta methods and seasonal tweaks, is in how many hours should aquarium lights be on.

Should you turn the light off at night?

Yes, always give your tank a dark period. Unlike the filter, which must run 24/7, the light must be off for a continuous block each night. Plants need darkness to respire, fish need rest, and a proper night period is essential for controlling algae. Never leave an aquarium light on around the clock. Full reasoning in should you turn aquarium lights off at night.

Spectrum and colour: WRGB, RGB and full spectrum

Light “colour” matters for both looks and plant growth. The terms you will see:

• Full spectrum - a balanced white light covering the range plants use; the safe all-round choice for planted tanks.
• WRGB - white plus separate red, green and blue diodes. Renders fish and plant colours richly and supports strong growth; the premium planted-tank option.
• RGB - colour-mixing diodes used mainly for visual effect and accent colour.
• Blue light - often included for a night/moonlight mode and for marine tanks; not a substitute for white light during the day.

For a planted tank that should look vivid, a WRGB or quality full-spectrum light is worth the spend. Learn the differences in WRGB vs RGB vs full spectrum, and what the blue setting is really for in is blue light good for an aquarium.

Lighting and algae: the balance

Almost every algae problem traces back to light, too much intensity, too many hours, or direct sunlight. Algae and plants compete for the same light and nutrients, so the goal is to give plants enough light to outcompete algae, and no more. The fixes are simple: cap the photoperiod at 6–8 hours, keep the tank out of direct sun, do not overfeed, and match intensity to your plants. If algae is already a problem, see the best aquarium light settings to prevent algae. A UV steriliser can clear stubborn green water, though it does nothing for plant growth.

How to choose a light for your tank size

Length and depth both matter. The light should span most of the tank’s length for even coverage, and a deeper tank needs a stronger light to push usable light to the substrate. As a rough India-market guide:

Buy a light rated for your tank length, and for planted tanks lean one tier higher in output. The detailed sizing method is in what size aquarium light do I need.

Waterproofing and safety

Water and electricity demand care. Choose lights rated for aquarium use, keep transformers and plugs above water level, and always run a drip loop so water cannot track down the cable into the socket. Submersible lights must be fully rated for underwater use. In humid and monsoon conditions across much of India, sealed, well-built lights last far longer. See waterproof and submersible aquarium lights.

Use a timer for consistency

The single best upgrade after the light itself is a simple plug-in timer. It gives your tank an identical photoperiod every day with zero effort, which keeps plants healthy and algae in check, and removes the “I forgot to switch it off” problem that fuels algae. Many modern LEDs have built-in timers and gradual sunrise/sunset modes. More in aquarium light timers and automation.

Putting it all together

• Fish-only tank: any basic LED sized to your tank, 6–8 hours on a timer, off at night.
• Low-tech planted: full-spectrum LED of moderate output, 7–8 hours, no direct sun.
• High-tech planted: high-output full-spectrum or WRGB, 8–10 hours with CO2, watch for algae.
• Every tank: a consistent photoperiod, a dark night period, and a timer.

Lighting works hand in hand with the rest of your setup, pair it with a good filter and, for planted tanks, the right fertiliser dosing for healthy, algae-free growth.

Frequently asked questions

What light is best for an aquarium?

A full-spectrum LED sized to your tank. For planted tanks choose a higher-output full-spectrum or WRGB LED; for fish-only tanks any quality LED is fine.

How many hours should I keep my aquarium light on?

6–8 hours a day for most tanks, on a timer. Fish-only tanks can run less; planted tanks usually need 7–8 hours.

Should I turn the aquarium light off at night?

Yes. Give the tank a continuous dark period every night. Plants need darkness to respire, fish need rest, and it helps control algae.

Do I need a special light for live plants?

Yes. Live plants need an adequate full-spectrum light to photosynthesise. A dim fish-only light will not keep most plants alive.

Will an aquarium light cause algae?

Too much light, high intensity, long hours, or direct sunlight is the main cause of algae. Cap the photoperiod and match intensity to your plants.

What is the difference between full spectrum and WRGB?

Full spectrum is a balanced white light; WRGB adds separate red, green and blue diodes for richer colour rendering and strong plant growth.

Can I use a normal LED or household light for my aquarium?

It is not recommended. Household lights are not designed for plant spectrum or for safe use around water. Use a light rated for aquariums.

Is blue light good for an aquarium?

Blue light is useful as a night or moonlight mode and in marine tanks, but it is not a substitute for white light for plant growth during the day.

What size light do I need for a 2 or 3 foot tank?

Choose a light rated to span most of the tank length, a 2 ft light for a 2 ft tank, 3 ft for a 3 ft tank and go one tier stronger for planted tanks.

Can I leave my aquarium light on 24/7?

No. Continuous light stresses fish, prevents plants from respiring, and strongly promotes algae. Always include a dark night period.

Do fish need darkness to sleep?

Yes. Fish rest during a dark period. A consistent day/night cycle keeps them healthier and less stressed.

What is a UV light for in an aquarium?

A UV steriliser clears green water and reduces waterborne pathogens. It does not grow plants and is separate from your display light.

Should I get a light with a timer?

Yes, strongly recommended. A timer gives a consistent photoperiod automatically, which keeps plants healthy and algae under control.

Why do my fish look washed out?

Usually weak or wrong-spectrum lighting. A full-spectrum or WRGB light dramatically improves how fish colours appear.

How far above the tank should the light sit?

Follow the maker’s guidance, but generally close enough for good intensity at the substrate without overheating; deeper tanks need stronger light or a closer mount.

New to planted tanks? Start with this guide, then read the planted lighting guide and our complete aquarium filter guide. Browse equipment in the Fish Bazaar store.