Gram staining technique is a microbiological staining method used in the separation of bacterial varieties. With this technique, bacteria are easily identified and classified. The reactions of bacteria stained with gram staining technique are common to the groups of bacteria that are similar in terms of growth. Especially in the use of drugs, the recognition of bacteria is an important issue. Some of the antibiotics affect, in particular, gram-positive bacteria, while others affect mostly gram-negative bacteria.

Gram-negative bacteria are those that do not retain crystal violet dye during gram staining. Gram-negative bacteria lose their blue color, while gram-positive bacteria continue to retain the blue color even after washing with alcohol. Therefore, gram positive bacteria are blue and purple bacteria that become very black under the microscope after going through the gram staining process.

A number of chemicals and feeds are supplied to fish in fish farms. These include the crystal violet chemical compound given to the fish eggs to be strong against bacteria, fungi, various viruses and parasites. After the new legal regulations prohibited the previously commonly used malachite green compound, today the crystalline violet compound is used as an effective disinfectant.

As in malachite green, the crystal violet compound is converted into two different forms by the metabolism. When it enters the cell quickly through the cell membranes, the leuco crystal changes to another form called violet.

In the laboratories, leukocrital violet dyestuff analyzes are carried out in aquaculture within the scope of chemical tests and LC-MS / MS method is used in these analyzes. Liquid chromatography - defined as a mass spectrometer, is a chemical analytical method that combines the mass analysis capabilities of the mass spectrometer with the physical separation properties of liquid chromatography. These studies are based on standards published by domestic and foreign organizations.