F - Aquarium Dictionary

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

Aquarium Fish Definition and Glossary

Fake Plants :
are made out of plastic or silk and are used for decorations in aquariums. They should be used with caution though... some fish species can tear their fins or snag their fins on sharp fake plastic plant edges. Silk plants are usually preferred. They can also be hard to keep clean. Obviously, live plants would be the best choice but for looks and functional reasons, these can be fine for decorative purposes. See:
Fake Plants
Plastic Plants

Silk Plants
Silk Plants

Ferts - Fertilzer :
ferts is short for fertilizer and is usually in reference to plant fertilizers such as NiloCG ThriveC, Root Tabs, API Leaf Zone, Seachem Flourish, etc.

Filter :
is a piece of aquarium equipment used to clean the aquarium water through mechanical, biological or chemical methods. Also see: Aquarium Filters.

Filter Floss :
is usually made of polyester material and used in the mechanical filtration of aquarium water to help remove particles, waste and debris from the water column. When bought in bulk it can be fairly inexpensive. For more info:
filter floss
Filter Floss

Fin Rot :
is a fish disease that causes the fish fins to rot away. This is a bacterial infection that is usually brought about by poor nutrition and poor water quality within the aquarium. It may also be caused by fin nipping coupled with poor water quality. Given good conditions (water, foods and no fin nippers) the fish fins may grow back. For way more details see: Fish Fin Rot

Fingerling :
is a baby, young, or very small fish.

Fin and Body Cure :
a powdered fish medication made by API that treats body slime, eye cloud, fin and tail rot, open red sores, gill disease, and hemorrhagic septicemia. See:
Fin and Body Cure
Fin and Body Cure

Finnex :
an aquarium product manufacturer that produces some of the more affordable and more popular LED fixtures for freshwater hobbyists. See:
Finnex LED

Fish Only - FO :
is a term that is often used to describe a saltwater tank that consists of fish only. There are no live rock, corals or other marine invertebrates present. These are very basic setups and can actually be a little harder to run than tanks employing live rock.

Fish Only With Live Rock - FOWLR :
is a term used to describe a saltwater tank using live rock. Fish are included in this saltwater aquarium setup, but there are no corals or invertebrates.

Flashing :
used to describe the quick darting or fish flashing against objects in the aquarium. This can be signs of the onset of a disease known as ich in your fish. Watch them closely and hopefully, if they are new fish, they are in a quarantine tank where you'll be able to treat them effectively. If not, it may be a good idea to start getting a quarantine tank ready.

Flourish :
is a planted aquarium supplement that provides micro and trace elements. This is used for the dosing of micro nutrients in planted tanks. See:

Flourite :
is a porous clay aquarium gravel for planted fish tanks that lasts for the life of the aquarium. See:
Seachem Flourite

Fluorescent Light :
is an aquarium light that uses electricity, mercury vapor and neon gas to produce ultraviolet light. These lights require a ballast to regulate the electrical flow to the lamps.

Fluidized Bed Filter :
an aquarium filtration device that forces water through a sand medium. As the aquarium water flows continuously through the sand, beneficial bacteria colonies attach themselves to the sand and it should increase the biological filtration capacity of the aquarium. There can be some potential problems with running these filters. They can become packed and turn into nitrate factories. Mechanical filtration of debris before the water enters the fluidized bed filter should help prevent this from happening though frequent monitoring and maintenance may be required.

Fluval :
an aquarium product manufacturer that makes a wide range of aquarium products. They have a very popular line of aquariums and canister filters. See below:
Fluval Canisters

Fluval 106, 206, 306, 406 :
is a line of canister filter models made by Fluval. See:
Fluval Canister Filter
Fluval 106, 206, 306, 406

Fluval Edge :
a fairly popular all in one type aquarium setup that includes LED lighting, filter and wiring all hidden in a decorative column. For more, see:
Fluval Edge
Fluval Edge

Fluval Spec :
an all-in-one aquarium setup kit that comes with LED lighting, powerhead and 3-stage filtration. A nice looking smaller sized aquarium:
Fluval Spec
Fluval Spec

Foam Fractionation :
a method of removing dissolved organics from the aquarium water. Also see: Protein Skimmer.

Frag :
short for coral fragment, refers to a small piece of coral. Corals can be very expensive and hobbyists will often frag their corals for trading with other hobbyists.

Frogbit :
is a floating aquarium plant considered good for planted tank beginners. More below:
Frogbit Plant

Frogspawn Coral :
see Frogspawn Coral

Fry :
can be thought of as free swimming baby fish. Baby fish need to be fed much smaller foods that can sometimes be difficult to acquire. Hikari First Bites is a popular food for many fish species fry:
Hikari First Bites
First Bites

Fugeray :
an aquarium LED light fixture made by Finnex for freshwater planted tanks. See:
Finnex FugeRay

Full Spectrum Light :
is a light that displays the entire spectrum of visible light, from violet to red. For example, sunlight is considered Full Spectrum.

Fungus :
usually shows up in the form of fine white colored threads after a fish has been stressed or suffered damage. Mouth fungus is also known as the dreaded columnaris. Fungus is bacterial and can be treated with an antibacterial such as API Fungus Cure:
Fungus Cure
Fungus Cure

Furan :
a fish medication for gram-positive and gram-negative bacterial diseases, including bacterial gill disease, open red sores, body slime and eye cloud, black molly disease (Flavobacterium columnaris) and fin and tail rot. For use in both freshwater and saltwater aquariums. This medication will not harm the biological filter. Note: This medication will cause a slight discoloration of water which can be removed with activated carbon.
API Furan

Fusion :
an aquarium water additive made by Seachem that provides two part calcium/alkalinity to help restore and maintain calcium and alkalinity levels. See:

FW :
abbreviation for the term "Freshwater".