A clear guide to the key terms used in marine fish keeping and buying
A powdered mix that replicates natural seawater chemistry. It is dissolved in tap water to create saltwater. The elemental balance is pre-adjusted, and specific gravity should be measured after mixing. Essential for regular water changes.
An instrument for measuring saltwater salinity. Available as a floating hydrometer or digital refractometer. Marine fishkeeping typically targets a specific gravity of 1.020–1.024, with regular checks needed to account for evaporation-related fluctuations.
A filtration device that uses fine bubbles to remove proteins and organic waste from the water. It is a cornerstone of marine aquarium water quality management, physically separating and exporting dissolved organics that filters alone cannot remove.
Natural porous rock colonized by diverse bacteria and microorganisms on its surface and interior. It forms the foundation of biological filtration and doubles as shelter for fish and an aquascaping material — a staple in marine aquariums.
The process of gradually matching the temperature and water chemistry between the bag water and the tank water when introducing new livestock. It is an essential step to prevent shock from abrupt environmental changes; the drip method is recommended.
An acclimation method using airline tubing to add tank water drop by drop into the bag or bucket. By slowly adjusting water chemistry over 1–2 hours, it minimizes stress on the fish and is considered the gentlest approach.
Keeping multiple fish species together in the same tank. Many marine fish are highly territorial, and incompatible pairings can lead to fighting and stress. Introduction order and size differences must also be considered.
A marine aquarium primarily designed around corals and other reef organisms. Reef-safe fish are often kept alongside the corals, and lighting and water quality management must be more precise than in a fish-only setup.
Short for Fish-Only tank — a marine aquarium that houses only fish without corals. Lighting and water quality requirements are simpler than in reef setups, making it a popular entry point for marine fishkeeping.
A separate tank used to temporarily isolate and quarantine newly purchased fish before adding them to the main display. Fish are observed for 1–2 weeks to prevent introducing diseases like ich, with medication administered as needed.
A filtration approach centered on live rock and a protein skimmer to create a near-natural ecosystem inside the tank. Also known as the Berlin Method, it relies on large quantities of live rock for biological filtration.
The practice of enhancing the vividness of a fish's body color. Methods include feeding foods rich in carotenoids or astaxanthin and adjusting lighting color temperature. A stress-free environment is also a key factor.