S - Aquarium Dictionary

Updated August 12, 2019
Author: Mike - FishLore Admin
Social Media: FishLore on Social Media

Aquarium Fish Definition and Glossary

short for Siamese Algae Eater.

Salinity :
is a measurement of the total amount of dissolved salts in saltwater. Measured with either a refractometer or less accurately with a hydrometer

Salt :
depends on the reference. In freshwater aquariums it is referring to regular aquarium salt like API Aquarium Salt. Whereas with saltwater tank references they are referring to salt mixes like Instant Ocean Salt Mix. Using salt in freshwater aquariums is sometimes a hotly debated topic. Proponents claim it helps fish breath by improving gill function and increases the stress coat on fish (API claims this as well). For more, see:
Aquarium Salt
Aquarium Salt

Sand :
sand is used for the substrate of the aquarium and it comes in many different forms. Tahitian Moon Sand, Pool Filter Sand, Play Sand, Black Diamond Blasting Sand are just a few different options and they all have their own particular applications. Certain fish species need and prefer a sand substrate. See sand options below:
School :
refers to the grouping behavior that certain fish species practice in order to avoid predation.

Seachem Focus :
an aquarium medication made by Seachem that is designed to treat internal bacterial and fungal diseases. See:
Seachem Focus
Seachem Focus

Sessile :
refers to organisms (invertebrates) that do not freely move around the tank (immobile) and they are attached to the substrate, live rock or other surface.

SG :
abbreviation for Specific Gravity.

Shrimp Pellets :
a fish food designed for bottom feeders like loaches and corydoras catfish. A popular brand is Wardley Shrimp Pellets (see below).
Shrimp Pellets
Shrimp Pellets

Silicone :
in reference to aquariums, refers to the type of glue used to seal fish tanks or aquarium equipment. Make sure any silicone used on the aquarium is aquarium safe silicone like below.
Aquarium Silicone

Spawn :
can be considered the period of time while fish are reproducing (breeding). It can also refer to the fertilized eggs or the release of eggs into the water column for fertilization.

Specific Gravity :
is a weight ratio of one liter of some substance compared to one liter of water and is temperature dependant. Saltwater aquariums need to be in the 1.021 - 1.025 range. Specific gravity can be measured with a hydrometer or a refractometer. See below:
Spirulina :
Spirulina is used as fish food and is a type of blue-green algae that is good for feeding to herbivorous fish.

Sponge Filter :
is an internal aquarium filter that is very popular with fish breeders for their easy maintenance and durability. It basically performs mechanical filtration and biological filtration. These filters consist of a sponge material that is attached to a power head like device that pulls aquarium water through the sponge. Larger particles are trapped in the sponge and beneficial bacteria can grow on and within the sponge. To clean a sponge filter all you have to do is ring it out in discarded tank water and it should be ready to go again.
Sponge Filter
Sponge Filters

abbreviation for Small Polyped Stony Corals.

Seachem Stability :
an aquarium water supplement made by Seachem that establishes the aquarium's biofilter in both freshwater and saltwater aquariums. The bacteria is non sulfur fixing and claims not to produce hydrogen sulfide. Stability helps prevent new tank syndrome.
Seachem Stability

Stealth Heater :
an aquarium heater made by Marineland that comes in sizes from 20 watts all the way up to 400 watts. See:
Stealth Heater
Stealth Heaters

Stingray :
depends on the context in which the word is used. It can either be a bottom-dwelling marine ray or a lighting fixture. More often than not on the forum though it is in reference to an LED lighting fixture made by Finnex. More below:
Finnex Stingray Light
Finnex Stingray

Stress Coat :
removes harmful chemicals from tap water and makes it safe for fish. Replaces fish's protective slime coating damaged by handling and shipping or from stress.
Stres Coat
Stress Coat

Strontium :
a trace element in natural saltwater that aids in calcerous algae growth. Also see the Saltwater Aquarium Supplements article.

Submersible :
used in reference to aquarium heaters. Most heaters these days are considered submersible, e.g. they can be placed completely under water, but make sure that your is indeed submersible. Below is an example of a submersible heater:
Submersible Heater

Substrate :
is the bottom of the aquarium and usually consists of rocks, driftwood, gravel, sand or mud (saltwater aquariums).
Sump :
is an aquarium that is connected to the main tank, often hidden below or behind the main display aquarium, that is used to increase the total amount of volume in the system and used to hide equipment such as protein skimmers, heaters, aquarium filters, chillers, etc. Here is an example of a decent sump on amazon.

SunSun :
an aquarium product manufacturer that makes affordable equipment for hobbyists. Their brand of canister filters are are fairly popular with hobbyists:
SunSun Canister Filter
SunSun Canister

Surgeonfish :
The Tang or Surgeonfish is common name for a saltwater fish species. They are nick named surgeonfish because of the scalpel like growths (blade like) at the base of the caudal peduncle which they use for aggression and defense.

SW :
abbreviation for Salt Water.

Symbiosis :
is when two different types of organisms live in close association (i.e. together). There are several different classes of symbiosis: mutualism, commensalism, parasitism, amensalism, neutralism and competition.