Growth Performance and Histomorphology of Intestine, Skin, Gills and Liver of Juvenile Colossoma macropomum Fed Diets Containing Different Levels of the Essential Oil of Nectandra grandiflora

Round 1

Reviewer 1 Report

This study was performed to investigate the influences of the essential oil on growth, histomorphology of intestine, skin, gills and liver in juvenile Colossoma macropomum. The experimental design is reasonable, and the results of this study provide a potential feed additive for Colossoma macropomum. Some details should be improved:

 1.     “histomorphometry and histomorphology” indicate a same thing, so suggest “histomorphology” was used in title.

2.     In this study, the growth performance was calculated in three stages (Day 10; Day 20; Day30). If the initial body weight of fish in Day 20 is the same as the final body weight of fish in Day 10, then it is expected that the values of W in Day 20 should be equal to "W in Day 10 + DC in Day 20". However, it seems that the results for W in Day 20 and Day 30 are not the same as expected. Please explain it.

3.     Are the values of SGR, FCR and PER in Day 30 were determined from day 20 to day 30? If this is the case, the statistical analysis method of one-way ANOVA may be incorrect. Because the initial body weights of fish during the period of day 20 to day 30 were significantly different among four treatments. The covariance analysis should be used.

4.     If the values of SGR, FCR, and PER in Day 30 were determined from Day 20 to Day 30, then using the statistical analysis method of one-way ANOVA may not be appropriate. This is because the initial body weights of fish during the period of Day 20 to Day 30 were significantly different among the four treatments. In this case, a covariance analysis should be used instead to provide a more accurate accurate and reliable statistical analysis.

５．This MS provide the histomorphology indexes to explain the improvement of immunity and digestive activities. However, to provide more direct evidence for these capacities, it would be beneficial to include the physiological parameters of fish, such as immunity and digestive enzyme activities. Adding these parameters would provide a more comprehensive understanding of the effects of the treatment on fish health and performance. Therefore, I suggest including the physiological parameters of immunity and digestive enzyme activities in the manuscript to strengthen the findings and conclusions.

Author Response

Comments from the editors and reviewers:

Editor:

During the technical check of your manuscript, we found that your
manuscript had a high similarity rate and we would therefore request
rephrasing. Please reduce the similarity rate below 30%.

R: Dear editor, thank you for your attention to our article. We considered the comment, reformulated the sentences that presented similarity and Professor Bernardo Baldisserotto used the tool that showed a similarity value of less than 30%.

Reviewer 1:

This study was performed to investigate the influences of the essential oil on growth, histomorphology of intestine, skin, gills and liver in juvenile Colossoma macropomum. The experimental design is reasonable, and the results of this study provide a potential feed additive for Colossoma macropomum. Some details should be improved:

1. “histomorphometry and histomorphology” indicate a same thing, so suggest “histomorphology” was used in title.

R: Thank you for your comment, the word histomorphometry was removed from the entire manuscript.

2. In this study, the growth performance was calculated in three stages (Day 10; Day 20; Day30). If the initial body weight of fish in Day 20 is the same as the final body weight of fish in Day 10, then it is expected that the values of W in Day 20 should be equal to "W in Day 10 + DC in Day 20". However, it seems that the results for W in Day 20 and Day 30 are not the same as expected. Please explain it.

R: Growth performance was calculated in the three stages, however there was no redistribution and balance in the initial weight between treatments at the beginning of the next stage. In brief, the respective animals from each treatment and replicate were weighed and maintained in their respective tanks/replicates/treatments.

Below are some articles that used the same methodology:

Santos, F. A., Boaventura, T. P., da Costa Julio, G. S., Cortezzi, P. P., Figueiredo, L. G., Favero, G. C., ... & Luz, R. K. (2021). Growth performance and physiological parameters of Colossoma macropomum in a recirculating aquaculture system (RAS): Importance of stocking density and classification. Aquaculture, 534, 736274.

Assis, Y. P. A. S., de Assis Porto, L., de Melo, N. F. A. C., Palheta, G. D. A., Luz, R. K., & Favero, G. C. (2020). Feed restriction as a feeding management strategy in Colossoma macropomum juveniles under recirculating aquaculture system (RAS). Aquaculture, 529, 735689.

Boaventura, T. P., Pedras, P. P., Santos, F. A., Ferreira, A. L., Favero, G. C., Palheta, G. D., ... & Luz, R. K. (2021). Cultivation of juvenile Colossoma macropomum in different colored tanks in recirculating aquaculture system (RAS): Effects on performance, metabolism and skin pigmentation. Aquaculture, 532, 736079.

Neto, R. V. R., Hashimoto, D. T., Corrêa, C. F., Enke, D. B. S., Gervaz, W. R., & Lattanzi, G. R. (2020). Performance of tambacu hybrid (♂ Piaractus mesopotamicus x♀ Colossoma macropomum) and its parental pacu (Piaractus mesopotamicus) evaluated in cages under different feeding programmes. Aquaculture Reports, 17, 100355.

3. Are the values of SGR, FCR and PER in Day 30 were determined from day 20 to day 30? If this is the case, the statistical analysis method of one-way ANOVA may be incorrect. Because the initial body weights of fish during the period of day 20 to day 30 were significantly different among four treatments. The covariance analysis should be used.

R: As answered in the previous question, the animals were kept in their respective tanks/treatments, and at the after of 10 and 20 days biometric data were collected to analyze growth throughout the experimental period. we used one-way ANOVA to verify the differences within each biometric (10,20 and 30 days). Here are some works that used the same method:

Santos, F. A., Boaventura, T. P., da Costa Julio, G. S., Cortezzi, P. P., Figueiredo, L. G., Favero, G. C., ... & Luz, R. K. (2021). Growth performance and physiological parameters of Colossoma macropomum in a recirculating aquaculture system (RAS): Importance of stocking density and classification. Aquaculture, 534, 736274.

Assis, Y. P. A. S., de Assis Porto, L., de Melo, N. F. A. C., Palheta, G. D. A., Luz, R. K., & Favero, G. C. (2020). Feed restriction as a feeding management strategy in Colossoma macropomum juveniles under recirculating aquaculture system (RAS). Aquaculture, 529, 735689.

Boaventura, T. P., Pedras, P. P., Santos, F. A., Ferreira, A. L., Favero, G. C., Palheta, G. D., ... & Luz, R. K. (2021). Cultivation of juvenile Colossoma macropomum in different colored tanks in recirculating aquaculture system (RAS): Effects on performance, metabolism and skin pigmentation. Aquaculture, 532, 736079.

ANOVA was applied because the treatments are not equidistant, so it would not be plausible to apply regression analysis.

4. If the values of SGR, FCR, and PER in Day 30 were determined from Day 20 to Day 30, then using the statistical analysis method of one-way ANOVA may not be appropriate. This is because the initial body weights of fish during the period of Day 20 to Day 30 were significantly different among the four treatments. In this case, a covariance analysis should be used instead to provide a more accurate accurate and reliable statistical analysis.

R: As answered in the previous question, the animals were kept in their respective tanks/treatments, and at the after of 10 and 20 days biometric data were collected to analyze growth throughout the experimental period. we used one-way ANOVA to verify the differences within each biometric (10,20 and 30 days). Here are some works that used the same method:

Santos, F. A., Boaventura, T. P., da Costa Julio, G. S., Cortezzi, P. P., Figueiredo, L. G., Favero, G. C., ... & Luz, R. K. (2021). Growth performance and physiological parameters of Colossoma macropomum in a recirculating aquaculture system (RAS): Importance of stocking density and classification. Aquaculture, 534, 736274.

Assis, Y. P. A. S., de Assis Porto, L., de Melo, N. F. A. C., Palheta, G. D. A., Luz, R. K., & Favero, G. C. (2020). Feed restriction as a feeding management strategy in Colossoma macropomum juveniles under recirculating aquaculture system (RAS). Aquaculture, 529, 735689.

Boaventura, T. P., Pedras, P. P., Santos, F. A., Ferreira, A. L., Favero, G. C., Palheta, G. D., ... & Luz, R. K. (2021). Cultivation of juvenile Colossoma macropomum in different colored tanks in recirculating aquaculture system (RAS): Effects on performance, metabolism and skin pigmentation. Aquaculture, 532, 736079.

ANOVA was applied because the treatments are not equidistant, so it would not be plausible to apply regression analysis.

５．This MS provide the histomorphology indexes to explain the improvement of immunity and digestive activities. However, to provide more direct evidence for these capacities, it would be beneficial to include the physiological parameters of fish, such as immunity and digestive enzyme activities. Adding these parameters would provide a more comprehensive understanding of the effects of the treatment on fish health and performance. Therefore, I suggest including the physiological parameters of immunity and digestive enzyme activities in the manuscript to strengthen the findings and conclusions.

R: Thank you for your suggestion, dear reviewer. However, these parameters were unfortunately not part of our planning for the respective work. We hope that in the near future we will be able to apply this type of analysis in this type of study.

Reviewer 2 Report

Manuscript ID: fishes-2641565

General comment: The manuscript provides novel information regarding the effect of supplementation of essential oil of Nectandra grandiflora in juvenile Colossoma macropomum diets. The study is relevant for the aquaculture industry. However, the manuscript should be rewritten in correct scientific English. The authors need to check consistency of citation style and abbreviations in the manuscript and decimal points in the tables. In the discussion, previously published results are not properly linked with the present results. In addition, there are some issues (see the comments listed below) that the authors should take into consideration. Therefore, I recommend consideration for acceptance of the manuscript for publication after minor changes.

Key words:

recirculating aquaculture system: not appropriate for the present study.

Introduction:

Line 48: EOs

Materials and methods:

Lines 83-89: It is not clear what were analyzed by GC.

Line 87: ‘Evaluation parameters were the same as described by Silva et al. (2016)’. Not clear.

Line 157: ‘Histological sections …’. Not a complete sentence.

Results:

Line 189, 205 and 211: ‘Different letters in rows’?

Figure 3: Please improve the quality of the figure.

Discussion:

Lines 228-231: Please remove these lines.

Lines 254-256: Please mention how the modulation of gut microbiota can contribute for greater performance.

Lines 285-291: ‘Juvenile Sparus aurata fed a diet containing 5 g/kg…’. Link this with the present results.

Lines 292-305: I would suggest to move this up to explain the growth performance results.

Lines 310-313: ‘Juveniles of yellow tail tetra…’ Link this with the present results.

The manuscript needs to be rewritten in correct scientific English.

Author Response

Reviewer 2:

General comment: The manuscript provides novel information regarding the effect of supplementation of essential oil of Nectandra grandiflora in juvenile Colossoma macropomum diets. The study is relevant for the aquaculture industry. However, the manuscript should be rewritten in correct scientific English. The authors need to check consistency of citation style and abbreviations in the manuscript and decimal points in the tables. In the discussion, previously published results are not properly linked with the present results. In addition, there are some issues (see the comments listed below) that the authors should take into consideration. Therefore, I recommend consideration for acceptance of the manuscript for publication after minor changes.

Key words:

recirculating aquaculture system: not appropriate for the present study.

R: Thanks for the comment. We replaced the keyword ´´recirculating aquaculture system`` with ´´Phytogenic additive``.

Introduction:

Line 48: EOs

R: The substitution was made directly in the text.

Materials and methods:

Lines 83-89: It is not clear what were analyzed by GC.

R: The main compounds of the essential oil of Nectandra grandiflora (EONG). We changed the sentence in line 84 to make this clearer.

Line 87: ‘Evaluation parameters were the same as described by Silva et al. (2016)’. Not clear.

R: More details added in lines 88-90.

Line 157: ‘Histological sections …’. Not a complete sentence.

R: Thanks for this observation. Sentence was rewritten.

Results:

Line 189, 205 and 211: ‘Different letters in rows’?

R: We replaced the sentence with ´´ Different letters indicate significant differences between treatments by one-way ANOVA and Tukey’s test (p<0.05).``

Figure 3: Please improve the quality of the figure.

R: We appreciate the comment. The Figure has been replaced with a better quality one.

Discussion:

Lines 228-231: Please remove these lines.

R: Lines have been removed directly in the text.

Lines 254-256: Please mention how the modulation of gut microbiota can contribute for greater performance.

R: We appreciate the comment. We added a sentence to complement how modulation of the intestinal microbiota contributes to fish performance.

Lines 285-291: ‘Juvenile Sparus aurata fed a diet containing 5 g/kg…’. Link this with the present results.

R: These lines (286-291) were rewritten to link our results with this study.

Lines 292-305: I would suggest to move this up to explain the growth performance results.

R: The changes were made directly to the text.

Lines 310-313: ‘Juveniles of yellow tail tetra…’ Link this with the present results.

R: the sentence (lines 313-316) was rewritten to link our results with this study.