Aquarium Abbreviations, Initialisms, Acronyms, and other Lingo


Using initialisms: If you're using an initialism, abbreviation, or acronym that isn't really widely used on the forum, it's a good idea to use the full term, followed by the abbreviation in parenthesis. After that, you can just use the abbreviation.
For example, if I'm talking about filters:
The hang-on-back (HOB) filter is extremely versatile. As its name suggests, the HOB hangs on the back...

This is a work in progress. Please feel free to add to it. Thanks to Lucy for the list she sent me. It tripled the list I had here.
Also, the fact that these are here does not mean you need to use them. Many of them are already kind of dead (there are two in the list that I've never seen before). I'm not including this so that everyone talks exactly the same, but rather for people to brush up on their aquarium speak.
Edit: I am editing some of the new answers into my own post. Others, I'm leaving out (though they'll still be in the post further down the list). I'm basing this largely on whether or not they're commonly used on the forum.


CPD = Celestial Pearl Danio
GBR = German Blue Ram
EBR = Electric Blue Ram
BR = Bolivian Ram
JD = Jack Dempsey (a type of Cichlid)
EBJD = Electric Blue Jack Dempsey
DG = Dwarf Gourami
WCMM = White Cloud MountainMinnow
F8 = Figure Eight Puffer
GSP = Green Spotted Puffer
BN = Bristlenose Pleco
CAE = Chinese Algae Eater
SAE = Siamese Algae Eater
RTS = Red Tail Shark
CD = Corydoras


RCS = Red Cherry Shrimp
CRS = Crystal Red Shrimp
MTS = Malaysian Trumpet Snail


HM = Half Moon
CT = Crown Tail
OHM = Over Half Moon
PK = Planket
VT = Veil Tail
DT = Delta Tail


ADF = African Dwarf Frog
ACF = African Clawed Frog


WPG = Watts per Gallon
T5, T8 = Size of light tube (5/8" or 1" diameter)
HO/VHO = (Very) High Output
MH = Metal halide
CFL - Compact Fluorescent
LED - Light Emitting Diode


BB = Beneficial Bacteria
DFS = Doctors Foster and Smith (a pet supply company)
MTS = Multiple Tank Syndrome (a communicable disease which causes aquarists to buy more and more tanks in order to accommodate more fish.)
NTS = New Tank Syndrome (more of an old school term from when less was known about the nitrogen cycle)
FOWLR = Fish Only With Live Rock (a type of marine aquarium)
SA = South American (Usually referring to the area for Cichlids)
CA = Central American (Usually referring to the area for Cichlids)
API = Aquarium Pharmaceuticals Inc. (Most often used to describe the API Master Test Kit)
HOB = Hang On Back (type of filter)
(P)WC = (Partial) Water Change
DIY = Do It Yourself
UGF = Under Gravel Filter
GPH = Gallons Per Hour (a reference to filter/pump power.)
LPS = Local Pet Store
LFS = Local Fish Store (not to be confused with a Petsmart, Petco, or Walmart, which are usually referred to by name and as "big chain" )
TSS = Tetra Safe Start (water conditioner/bacterial additive)
AC = Activated Carbon
FW = Fresh Water
SW = Salt Water
BW = Brackish Water
FTS = Full Tank Shot. Used to describe a photo showing the whole tank
Q or QT = Quarantine Tank
DW = Driftwood
IAL = Indian Almond Leaves (often used to lower pH)

Water Chemistry

pH = potential of Hydrogen, a scale measuring the acidity or alkalinity of liquid
NH3 = Ammonia
NH4 = Ammonium (less toxic than ammonia)
NO2 = Nitrites
NO3 = Nitrates
PO4 = Phoshpate
Ca = Calcium
Mg = Magnesium
Sr = Strontium
Fe = Iron
PPT/PPM = Parts per Thousand/Million
mg/L = milligrams per litre. 1 mg/L = 1 PPM
TDS = Total Dissolved Solids
Alk = Alkalinity (also known as KH) - measure of carbonate hardness
dKH = degrees of Carbonate Hardness. 1 degree = 17.9ppm
dGH = degrees of General Hardness. 1 degree = 17.9ppm
SG = Specific Gravity. Typically used in Saltwater tanks as a measure of salt content
RO/DI = Reverse Osmosis / De-Ionisation (a process that creates nearly pure water)
GH = General Hardness
KH = Carbonate Hardness
PPM = Parts Per Million, same as mg/L


CO2 = Carbon Dioxide (plants breathe carbon dioxide and turn into oxygen)
NPK = Nitrogen Phosphate Potassium - K is the symbol for Potassium on the Periodic table. NPK are the three major elements for plants


IDK = I Don't Know
LOL = Laugh Out Loud
ROFL/ROTFL = Rolling on the floor laughing
IMO /IMHO = In My (Humble) Opinion
FWIW = For What It's Worth
FYI = For Your Information
BTW = By The Way
IME = In My Experience
OT = Off Topic
OP = Original Poster/post
IIRC = If I Recall Correctly
FTW = For The Win
FS = For Sale
WTB = Want to Buy
B/S/T/F = Buy, Sell, Trade, Free
TIA = Thanks In Advance


This list is really aimed at the stuff Fishloreans use.

It is not meant to be comprehensive, unlike the definitions page. This was just meant to hold a few of the most commonly used acronyms and initialisms. I'll be thinning the list out pretty soon, I think, as it's getting so long as to be useless.

I think the best way to be understood is to use the full term. If someone uses a term you don't understand, ask. Neither takes very long.

Similar Aquarium Threads

Chuck Wheat
  • Question
  • Stuartb90
  • pH
Jocelyn Adelman

Latest Aquarium Threads

Top Bottom