Do saltwater and freshwater compatibility rules differ?
Written by
John Williams
Reviewed by
Prof. David Walsh, Ph.D.Saltwater compatibilities have much stricter rules: a marine aquarium must be nicely aerated! Mixed in the water must be between 1.020 and 1.025 specific gravity salt. Saltwater fish need tanks considerably larger with a size of at least 30 gallons necessary at the start. The larger system becomes difficult to make sure the parameters are stable; even the slightest deviation can affect some especially delicate marine species.
Reef Safety
- Many fish nibble or damage coral structures
- Choose species verified as reef-safe
- Example: Clownfish coexist with anemones
Symbiotic Relationships
- Cleaner fish provide essential parasite removal
- Certain shrimp form partnerships with gobies
- Mandarin fish need established copepod colonies
Salinity Precision
- Marine fish tolerate narrower salinity ranges
- Daily testing prevents osmotic shock
- Automatic top-off systems maintain stability
Reef compatibility. Many colorful fish, such as butterflyfish, feed on coral polyps. Always check that they're reef-safe before adding them to your tank. Personally, I stick to charts dedicated solely to the marine world and take note if they indicate which corals it may eat. I've lost some rather expensive corals to incompatible fish before...
Symbiotic relationships are essential to many marine communities. Cleaner wrasses rid larger fish of parasites. Pistol shrimp dig burrows for gobies. These creatures have learned to depend on one another: miss a partner and the other becomes vastly stressed, sometimes even physically deteriorating. The writings on the saltwater chart always mention them.
Salinity control − You need to check this daily; that's right, daily, and not with a hydrometer! Just a tiny change in salinity and, zap, you get osmotic shock! We use a digital refractometer, and it's best to check it a few times a week. It's handy to top off the water that has evaporated with fresh RO water, which is always salt-free. None in the display tanks, please.
Tank maturity is even more of an issue with saltwater tanks. Only well-established tanks can support copepod colonies, which are more suitable for the more finicky mandarin fish. Newer tanks won't have the necessary microfauna for these specialized eaters. Wait at least six months before adding sensitive fish. Test copepod levels by observing with a flashlight at night. This additional waiting allows for the avoidance of starving those finicky marine eaters.
Read the full article: Fish Compatibility Chart Ultimate Guide
