Registration Dossier

Administrative data

Endpoint:
additional ecotoxicological information
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No GLP, no guidelines followed, poorly details on test conditions Read across from a similar substance which has the same main component and with a different counter ion that doesn't influence the characteristics related to the specific end-point
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1983

Materials and methods

Principles of method if other than guideline:
Duplicate lots of 250 rainbow trout eggs were treated daily with malachite green oxalate at a low concentration, weekly at a high rate, or every other day at an intermediate concentration; control fish were untreated. Treatments began after the eggs had water-hardened and continued until 24 hours before eggs in the control lots began to hatch. Treatments over the 34- day incubation period. Eggs were incubated in standard Heath trays provided with a common water source (12°C) but eacht ray had a separated rain. The effluent from a treated lot was not allowed to flow through the trays containing other lots of developing eggs. Time to hatching, percent hatch, survival, and morphology were determined for each lot of eggs and larvae. All hatched fish received the same ration and were reared for 21 days after feeding began, after which they were all examined for anomalies.
Type of study / information:
Eggs treatment

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material: malachite green oxalate
- Form: crystals
- Source: Matheson, Coleman and Bell

Results and discussion

Any other information on results incl. tables

Incubation of the various lots of rainbow trout eggs progressed normally. No stresses due to temperature, low oxygen, lack of flow, or poor water quality occurred. All lots of eggs treated with malachite green experienced a delay in hatching. Lots 5 and 6 had the shortest delay (5 days) and Lots 3 and 4 the longest observed effect (8 days).

At 3 weeks after hatching, all lots were examined for gross abnormalities such as head or jaw deformities, curvatures of the spine, missing fins, or a bob-tailed condition.

Frequencies of abnormalities were 34% in Lots 3 and 4; 27% in Lots 5 and 6; 20% in Lots 1 and 2 and were significantly different from that in the untreated controls( 7%) at (P < 0.05). Growth was significantly depressed in all treated groups( P <0.05).

Response of incubating Rainbow trout eggs to treatments with Malachite Green

Lots of MG treatment         
  1 and 2 3 and 4 5 and 6  7 and 8 
Response measured 1 mg/L; 1 hour daily (30 treatments) 3 mg/L; 1 hour every other day (15 treatments)  5 mg/L; 1 hour weekly (5 treatments)  Untreated controls 
Median time to eyed stage in days  18 23 23 18
Percent of eggs reaching eyed stage 72 66  60 70 
Percent hatch 68 96 82 70 
Median time to hatching in days 42 42  37  34
Mean total length of larvae at 21 days (mm) 13 12  16  18 
Percent deformities among larvae through 21 days 20 34  27 

Applications of Malachite Green (MG) on incubating rainbow trout eggs reduced the percent of eggs that reached the eyed stage, increased the time from fertilisation to hatching, reduced the average size of larvae, and caused a significant increase in the percent of larvae with deformities. However the percent of eyed eggs that hatched increased, perhaps as a result of control of fungal infections. The use of malachite green in fish hatcheries, thus, can result in significant losses of eggs and larvae. This loss can probably be offset by starting an increased number of eggs. Deformed larvae would not be expected to survive so the true number of larvae lost to MG effects is likely to be underestimated in a hatchery situation

Applicant's summary and conclusion

Conclusions:
Applications of Malachite Green (MG) on incubating rainbow trout eggs reduced the percent of eggs that reached the eyed stage, increased the time from fertilisation to hatching, reduced the average size of larvae, and caused a significant increase in the percent of larvae with deformities.
Executive summary:

Duplicate lots of 250 rainbow trout eggs were treated daily with malachite green oxalate at a low concentration, weekly at a high rate, or every other day at an intermediate concentration; control fish were untreated. Treatments began after the eggs had water-hardened and continued until 24 hours before eggs in the control lots began to hatch. Treatments over the 34- day incubation period. Eggs were incubated in standard Heath trays provided with a common water source (12°C) but each ray had a separated rain. Time to hatching, percent hatch, survival, and morphology were determined for each lot of eggs and larvae.

Conclusion

Applications of Malachite Green (MG) on incubating rainbow trout eggs reduced the percent of eggs that reached the eyed stage, increased the time from fertilisation to hatching, reduced the average size of larvae, and caused a significant increase in the percent of larvae with deformities. However the percent of eyed eggs that hatched increased, perhaps as a result of control of fungal infections. The use of malachite green in fish hatcheries, thus, can result in significant losses of eggs and larvae. This loss can probably be offset by starting an increased number of eggs. Deformed larvae would not be expected to survive so the true number of larvae lost to MG effects is likely to be underestimated in a hatchery situation.