Your marine aquarium questions, answered.
From first tank setup to coral selection and finding your nearest TMC stockist — expert guidance from the UK's leading marine aquatics specialist.
What fish can I keep with a clownfish?
Clownfish compatibility guide
Beginner Friendly - Compatibility Guide - Livestock
Overview
Providing a host anemone (Entacmaea quadricolor is often cited as the hardiest choice) can help reduce clownfish territorial behaviour in some cases, as they may focus aggression on defending the anemone rather than the whole tank. Note that E. quadricolor (Bubble Tip Anemone) is best suited to established, stable systems and is not recommended for newly set-up tanks."
Compatibility at a glance
Good Tankmates
Royal Gramma · Firefish Goby · Watchman Goby · Banggai Cardinalfish · Fairy Wrasse · Blenny species · Dartfish · Mandarin (mature, established reef)
Use Caution
Dottybacks (territorial) · Six-line Wrasse (may nip) · Large Angelfish · Hawkfish (may eat small ornamental shrimp) · Multiple clownfish pairs (unless bonded)
Avoid
Lionfish · Grouper · Larger Triggerfish · Pufferfish · Moray Eels · Large Aggressive Wrasse species
Hosting & anemone advice
Providing a host anemone (Entacmaea quadricolor is the hardiest choice) significantly reduces clownfish territorial behaviour, as they'll focus aggression on defending the anemone rather than the whole tank. In the absence of a suitable anemone, many clownfish will adopt a Euphyllia coral, large Xenia colony, or even a powerhead as a proxy host. Captive-bred clownfish are less instinctively driven to host and often settle without one.
How do I cycle a marine tank?
Beginner setup guide — nitrogen cycle
Beginner Guide - Water Chemistry - Tank Setup
What is the nitrogen cycle?
Every marine aquarium runs on bacterial biology. Ammonia (NH₃) — produced by fish waste, uneaten food, and decaying matter — is toxic. The nitrogen cycle establishes two bacterial colonies: Nitrosomonas, which converts ammonia into nitrite (NO₂⁻), and Nitrospira, which converts nitrite into nitrate (NO₃⁻). Nitrate is far less toxic and is removed via water changes and macroalgae. Without this cycle, your tank cannot sustain fish life.
Step-by-step: cycling your tank
-
Set up the system.
Fill with RO/DI water, mix quality synthetic salt to SG 1.025–1.026, run your filtration, heater, and skimmer. Allow temperature and salinity to stabilise before adding anything. -
Introduce an ammonia source.
Add a raw prawn in a mesh bag, a measured dose of pure ammonia (target 2–3ppm), or a bacterial starter culture. This seeds the cycle without stressing livestock. -
Add live rock or a starter culture.
Quality live rock from a mature system introduces billions of established bacteria and is the single biggest time-saver. TMC bacterial starter products can reduce cycle time from 6 weeks to under 2. -
Test every 48 hours.
Monitor ammonia, nitrite, and nitrate with a reliable liquid test kit. Log your readings — the curve tells you exactly where you are in the process. -
Wait for the peak-and-drop.
Ammonia spikes first, then nitrite rises as ammonia falls. Nitrate rises as nitrite falls. This process typically takes 4–8 weeks without a starter culture, 1–3 weeks with one. -
Confirm completion.
Both ammonia and nitrite must read 0ppm across two consecutive tests. Perform a 30–40% water change to knock back nitrate, then stock slowly — adding all fish at once will spike ammonia and break the cycle.
Target water parameters (post-cycle)
Ammonia: 0ppm · Nitrite: 0ppm · Nitrate: <20ppm (reef: <5ppm) · pH: 8.1–8.3 · Temperature: 24–26°C · Salinity: SG 1.025–1.026 · Alkalinity: 8–10 dKH
What's the difference between soft and hard corals for beginners?
Beginner coral selection guide
Beginner Friendly - Reef Keeping - Coral Care
The core difference
The fundamental distinction is skeletal structure. Soft corals (Order Alcyonacea) have no rigid calcium carbonate skeleton — they're supported by water pressure and small internal spicules. Hard corals (Order Scleractinia) secrete a calcium carbonate base, which is literally the stuff reef structures are built from. This physical difference cascades into dramatically different care requirements.
Side-by-side comparison
| Factor | Soft Corals | LPS Hard Corals | SPS Hard Corals |
|---|---|---|---|
| Difficulty | Easy | Intermediate | Expert |
| Water quality tolerance | Moderate variation OK | Stable parameters needed | Pristine, stable required |
| Lighting requirement | Low–Medium PAR | Medium PAR | Medium–High PAR |
| Flow requirement | Low–Moderate | Moderate | High, random flow |
| Dosing requirement | Usually none | Calcium/Alk helpful | Ca/Alk/Mg dosing essential |
| Common beginner species | Mushrooms, Zoanthids, Leather corals, Xenia, Star Polyps | Hammer, Torch, Frogspawn, Brain corals, Bubble coral | Acropora, Montipora, Stylophora, Pocillopora |
| Best starting point? | Yes — start here | After 6–12 months | Experienced reefkeepers only |
TMC recommendation for beginners
Start with a soft coral reef — leather corals (Sarcophyton), mushrooms (Discosoma and Rhodactis), and zoanthids are forgiving of the minor parameter swings every new reef keeper encounters. Once your system is stable and your chemistry knowledge is solid (6–12 months), introduce a Euphyllia LPS — the hammer or torch coral is widely regarded as the gateway hard coral. Reserve SPS for when you can test and dose daily without it feeling like homework.
What marine fish are captive bred in the UK?
TMC OLAS captive-bred marine fish UK
All Levels - Sustainability - TMC OLAS
Why captive-bred matters
Captive-bred marine fish are healthier, better adapted to aquarium conditions, and free from the stress of wild capture and international transit. They arrive eating prepared foods, are accustomed to tank water chemistry, and carry a significantly reduced risk of wild-origin pathogens. From a conservation standpoint, buying captive-bred helps reduce demand from wild reef collection. TMC's OLAS (Ocean Life Aquaculture Station) programme is the UK's most established marine aquaculture operation, producing captive-bred livestock available exclusively through authorised TMC stockists.
Captive-bred species available in the UK via TMC OLAS
Clownfish
Amphiprion ocellaris, A. percula + designer morphs
Multiple colour morphs available. Pairs can be requested. The most widely captive-bred marine fish in the UK.
Multiple colour morphs available. Pairs can be requested. The most widely captive-bred marine fish in the UK.
OLAS Bred
Orchid Dottyback
Pseudochromis fridmani
Less aggressive than wild-caught individuals. Intense purple colouration. Hardy, reef-safe with caution around small shrimp.
Less aggressive than wild-caught individuals. Intense purple colouration. Hardy, reef-safe with caution around small shrimp.
OLAS Bred
Neon Goby
Elacatinus oceanops
Natural cleaner fish. Immediately accepts frozen foods. Excellent for small reef systems.
Natural cleaner fish. Immediately accepts frozen foods. Excellent for small reef systems.
OLAS Bred
Banggai Cardinalfish
Pterapogon kauderni
IUCN Vulnerable in the wild — captive-bred stock is the ethical choice. Peaceful, slow-moving, reef-safe.
IUCN Vulnerable in the wild — captive-bred stock is the ethical choice. Peaceful, slow-moving, reef-safe.
OLAS Bred
How to identify captive-bred stock
Always ask your retailer to confirm captive-bred origin. Authorised TMC stockists can show the TMC Specimen Certification and OLAS designation for qualifying livestock. Captive-bred fish typically: accept dry/frozen foods immediately, display no signs of capture stress, and are noticeably bolder around humans than wild-caught equivalents.
How do I find a local stockist that sells TMC products?
Where to buy TMC products near me · dealer locator
All Levels - Dealer Locator - UK & EU
How to find your nearest TMC retailer
You can shop TMC products directly online at tropicalmarinecentre.com and collect your order from your nearest participating local fish shop through our Click & Collect programme. Simply browse the full range, select your preferred local store at checkout, and pick up your order when it's ready — with the added benefit of expert advice in-store.
To find your nearest participating store, use the [Find Your Nearest Dealer] tool on our website. Authorised retailers carry AquaRay LEDs, Vecton UV sterilisers, GroTech dosing systems, OLAS livestock, TMC Premium Foods, and more.
Want to know more about how Click & Collect works? Visit our [Support Your Local Fish Shop page].
Use the Dealer Locator
Visit tropicalmarinecentre.com and use the postcode-based dealer locator to find authorised stockists near you.
Contact the Trade Team
If you're a retailer looking to become a TMC stockist, contact our trade sales team directly to discuss account setup.
Look for TMC In-Store
Authorised retailers carry AquaRay LEDs, Vecton UV sterilisers, GroTech dosing systems, and OLAS livestock.
Products to look for in-store
AquaRay LED Lighting — TMC's own award-winning reef LED range · Vecton UV Sterilisers — the UK's leading UV steriliser brand · GroTech dosing systems · OLAS captive-bred livestock (clownfish, dottybacks, cardinals) · TMC Premium Foods and water treatments.
