What to Know Before Keeping Marine Fish
A comprehensive guide for first-time marine fish keepers covering tank selection, equipment, water quality, recommended species, and costs.
1Choosing Tank & Equipment
Marine fish keeping requires more equipment than freshwater. A minimum 60cm tank is recommended for water quality stability.
Tank Size
60-90cm recommended for beginners. Larger volume means more stable water. Overflow is ideal, but canister filters also work.
Filtration System
Canister filter or overflow system. A protein skimmer is nearly essential for marine tanks, removing organics via foam fractionation.
Lighting
Fluorescent or LED is sufficient for fish-only tanks. Coral-spectrum LEDs are needed if you plan to keep corals too.
Flow & Temperature
Marine fish prefer moderate flow. Use flow pumps for oxygen and circulation. Maintain 24-26C; a chiller is needed in summer.
2Saltwater Mixing & Water Quality
Mixing Saltwater
Dissolve salt mix in dechlorinated tap water or RO water. Mix thoroughly in a bucket before adding to the tank. Check specific gravity with a refractometer.
Specific Gravity
Fish-only tank: 1.020-1.023. With corals: 1.024-1.026. Top off with RO water as evaporation raises salinity.
Ammonia, Nitrite, Nitrate
Ammonia and nitrite must be 0ppm. Nitrate should be below 20ppm. Test regularly with kits, especially during cycling.
Water Change Frequency
Change 10-20% every two weeks. Prepare temperature and salinity-matched saltwater in advance.
pH Management
Maintain 8.0-8.4. Some fluctuation between lights-on and lights-off is normal. Check KH if swings are large.
Temperature
Keep 24-26C stable. Rapid changes cause ich. Match water temperature carefully during changes.
3Beginner-Friendly Marine Fish
Clownfish (Ocellaris)
Popular thanks to the movie. Hardy and easy to keep. Enjoy the symbiosis with anemones. Captive-bred specimens are especially robust.
Blue-Green Chromis
Small, vibrant blue-green fish. Extremely hardy and beautiful in schools. Perfect pilot fish.
Firefish
Beautiful white and orange coloring with a distinctive tall dorsal fin. Peaceful and mixes well.
Yellow Tang (Juvenile)
Vibrant yellow accent for your tank. Eats algae, helping control growth. Needs a larger tank as it grows.
Blue Devil Damselfish
Vivid blue and very hardy. Slightly aggressive, so choose tankmates carefully.
Pajama Cardinalfish
Silver with unique black spots. Peaceful and easy to keep, best in groups.
4Supplies Checklist
Tank & Filtration
- Tank (60cm+ recommended)
- Tank stand
- Canister filter or sump
- Protein skimmer
- Live rock
Water Quality
- Salt mix
- Refractometer
- Test kits
- Water conditioner (RO preferred)
- Buckets & siphon hose
Temperature & Lighting
- Heater with thermostat
- Chiller (for summer)
- LED lighting
- Thermometer
Other
- Flow pump
- Air pump
- Fish net
- Cleaning tools (algae scraper)
- Isolation box
5Initial & Monthly Costs
Initial Cost Estimates
Monthly Cost Estimates
Monthly marine fish keeping costs typically run 5,000-15,000 yen. Adding corals will increase costs due to additives and lighting electricity.
6Choosing a Reliable Seller
Prefer Captive-Bred
Captive-bred fish are hardier and often accept prepared foods better. Especially recommended for clownfish.
Check for Treatment
Choose sellers who quarantine and treat fish after receiving them to prevent diseases like ich.
Packaging & Shipping Care
Temperature management and stress reduction are critical. Look for insulated packaging, oxygen, and seasonal temperature control.
Reviews & After-Sale Support
Check reviews and choose sellers who handle post-arrival issues. Sellers offering care advice are a plus.
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