Triphenylmethane dyes in aquaristics

All of these compounds are active against parasites, ciliates, protozoa, fungi and in some cases bacteria. Some compound from this group is therefore likely to be present in any spotting disease preparation.

Caution: All of the following compounds, with the exception of methylene blue, are suspected of being carcinogenic!

Triphenylmethane dyes

Malachite green

R1 = -CH3, R2 = -H

IUPAC: N,N-Dimethyl-4-[p-(dimethylamino)-diphenylmethylene]-2,5-cyclohexadienylidenammonium chloride or -oxalate (1/2 eq.)
C.I.: 42000; Basic Green 4 / also called Diamant Green
Molecular formula: C23H25N2Cl (MW: 364.92) bzw. C24H25N2O2 (MW: 373.47)

Brilliant Green

R1 = -CH2CH3, R2 = -H

IUPAC: N,N-Diethyl-4-[p-(diethylamino)-diphenylmethylene]-2,5-cyclohexadienylidenammonium hydrogensulphate
C.I. 42040; Basic Green 1 / also called Ethyl green or Malachit green G
Molecular formula: C27H34N2O4S (MW: 482.64)

Crystal Violet

R1 = -CH3, R2 = -N(CH3)2

IUPAC: N,N-Dimethyl-4-[p,p'-bis(dimethylamino)-diphenylmethylene]-2,5-cyclohexadienyliden-ammonium chloride
C.I.: 42555; Basic Violet 3 / also called Hexamethylpararosaaniline chloride or Methyl violet 10B
Molecular formula: C25H30ClN3 (MW: 407.98)

Methylene Blue

Methylene Blue

IUPAC: 3,7-Bis(dimethylamino)phenothiazinylium chloride
C.I. 52015; Basic Blue 9 / Tetramethylthionine chloride, Methylthionium chloride
Molecular formula: C16H18ClN3S (MW: 319.85)

Efficacy

Against Costia, Chilodonella, Trichodina, Saprolegnia, Cryptobia and Trypanosoma. Also popular as a preventative and against spawn fungus.
The 1% solution (10 g/litre) or, if less is required, the 0.1% solution (1 g/litre) in water is used. The solution can only be kept for a long time if it is protected from light.

Dosage

  1 % solution 0.1 % solution
Against spawn fungus 0.3 ml / 10 l 3 ml / 10 l
Against infections after transport 0.5 ml / 10 l 5 ml / 10 l
Normal dose (treatment in the tank)
After 5 days carbon filtration
1.0 ml / 10 l 10 ml / 10 l
Increased dose (treatment in extra tank)
Cancel after 3 days
3.0 ml / 10 l 30 ml / 10 l
Short bath 20.0 ml / 10 l 200 ml / 10 l