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Article
Peer-Review Record

Effect of Commercial Diets on Growth and Digestive Physiology in Guppies (Poecilia reticulata)

Aquac. J. 2025, 5(3), 10; https://doi.org/10.3390/aquacj5030010
by Yael José Trejo-Sánchez 1, Graciela María Pérez-Jiménez 1, Gabriel Núñez-Nogueira 2, Luis Daniel Jiménez-Martínez 3, Otilio Méndez-Marín 1, Gloria Gertrudys Asencio-Alcudia 1, Uriel Rodríguez-Estrada 1,4, Rafael Martínez-García 1, Carlos Alfonso Álvarez-González 1,*,† and César Antonio Sepúlveda-Quiroz 1,5,*,†
Reviewer 1:
Reviewer 2: Anonymous
Reviewer 3:
Aquac. J. 2025, 5(3), 10; https://doi.org/10.3390/aquacj5030010
Submission received: 2 May 2025 / Revised: 11 June 2025 / Accepted: 3 July 2025 / Published: 8 July 2025

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The present manuscript did the research on the effect of four randomized commercial diets on growth and digestive physiology in guppies and it tried to determine whether commercial feeds formulated for ornamental fish and aquaculture cover the nutritional requirements. The ms was written fluently, and the material and methods was written correctly. While there are some comments before it is accepted, being followed.

(1)  There are many types of ornamental fish feed on the market, and you have only selected three of them. Are they scientifically representative for the design of the experiment?

(2) As for the ornamental fish, the rich nutrients for their better growth is important, while the ornamental character is still important for their value, furthermore the nutrients in T1 had high protein content, being 42%, and this group had the lowest dietary lipids, being 5%, which is probably fit for the health of the fish to avoid obesity. So, even the growth index value was not high in T1, the present experiment could not get the conclusion that T1 is not a kind of good diet for puppies. The same as the T3. The four diets were different in many aspects, that's the reason to be difficult to get the conclusion that which diet was best or not or which diet was the most fittest one.   

(3) As the experiment did the histological analysis,  it's better to put the figure of the liver and intestine in the result.

  (4) As the nutrients in the four diets was different, the food manufacturing and effects on fish in the discussion would be not appropriate.

All in all, as the present manuscript was written fluently and the result would probably attract the interests of some reader, especially the consumers, if they have the chance and spare time to read, the ms could be accepted with the adding of the figure of liver and intestine. 

Author Response

Manuscript ID: aquacj-3651299  

Title:Effect of commercial diets on growth and digestive physiology in guppies (Poecilia reticulata)

Response to Reviewer 1 Comments

Dear Reviewer,

Thank you very much for your valuable comments and questions. We have revised our manuscript according to your suggestions. Our responses are as follows:

Reviewer #1: The present manuscript did the research on the effect of four randomized commercial diets on growth and digestive physiology in guppies and it tried to determine whether commercial feeds formulated for ornamental fish and aquaculture cover the nutritional requirements. The ms was written fluently, and the material and methods was written correctly. While there are some comments before it is accepted, being followed. There are many types of ornamental fish feed on the market, and you have only selected three of them. Are they scientifically representative for the design of the experiment?

Thank you for your comments. We agree with what you say. There are many types of ornamental fish feeds on the market; evaluating them all is complicated. However, the selection was based on using the most common feeds, from different brands and at different prices, thus trying to cover a broad spectrum of possibilities. Furthermore, brands with the most nutritional information on the label were chosen, and as you can see, such information is limited. This increases our motivation for this work. It should be noted that this work has no promotional purposes for any brand; we are only interested in the effects on organisms and the well-being they can generate.

Reviewer #1: As for the ornamental fish, the rich nutrients for their better growth is important, while the ornamental character is still important for their value, furthermore the nutrients in T1 had high protein content, being 42%, and this group had the lowest dietary lipids, being 5%, which is probably fit for the health of the fish to avoid obesity. So, even the growth index value was not high in T1, the present experiment could not get the conclusion that T1 is not a kind of good diet for puppies. The same as the T3. The four diets were different in many aspects, that's the reason to be difficult to get the conclusion that which diet was best or not or which diet was the most fittest one.   

We appreciate your comment. Indeed, all the diets used present nutritional variability. This is due to being able to analyze the most representative options on the market (detailed in the previous response). Although protein levels vary 4% between the minimum and maximum values ​​in the diets used, the quality and origin of the protein used in the diet formulation are unknown. This is relevant because plant-based protein may be used with some antinutrients, which is not appropriate for animal growth and well-being. The same can occur with lipids, where the origin of the lipids used is unknown. If we only compare T2 and T4, the treatments with the greatest growth, with a variability of 1% in protein and 5% in lipids in the diets, survival shows that T4 is better (98%) than T2 (82%), with a 16% difference. In enzyme activity, T4 was better than T2, which coincides with digestibility, where T4 is better than T2. Likewise, T4 presents better histological results. This all becomes even more relevant since T4 is a diet specifically for trout (a farmed species), and the cost per kilo is extraordinarily lower than T2 and the other diets (lines 327-329). We assume this discrepancy in results is due to the manufacturing process, the quality of the ingredients, or diet formulation. In either case, animal welfare may be compromised.

Reviewer #1: As the experiment did the histological analysis,  it's better to put the figure of the liver and intestine in the result.

Thank you for your suggestion, we added a figure with representative images of our histological analysis.

 Reviewer #1: As the nutrients in the four diets was different, the food manufacturing and effects on fish in the discussion would be not appropriate.

Thank you for your comment. We considered discussing the manufacturing process of commercial ornamental fish feeds, as it is a highly secretive and understudied process. With this, we hope to encourage more studies evaluating this variable and its potential effects on ornamental fish. We also made modifications and improved the discussion section.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors wrote clearly throughout the text, so this was not a difficult read overall. I understood everything that the study was about.

My biggest request of the authors is that they pass this manuscript to a native English speaker with the mission of decreasing the use of so many commas and the unnecessary use of semi-colons. This is with the exception of the materials and methods, which I feel that the authors may have already passed this manuscript to a native English speaker because this section was written and structured perfectly in my opinion. 

Other things to look out for:

-make sure you list your units for all numbers where necessary

-make sure that you italicize the scientific names and "in vitro", among anywhere else that may be necessary.

-Remove the first sentence of the abstract, I do not think it is necessary

-Line 42, as an example: “The ornamental fish encompasses…”. Should this be ornamental fish industry? Look out for things like this.

Other than these points, it was a well written manuscript.

Comments on the Quality of English Language

If the authors take care of what I said, it would be a perfect manuscript. If they at least take care of the excess use of commas and use of semi-colons, it will still be a very good manuscript.

 

Author Response

Manuscript ID: aquacj-3651299  

Title:Effect of commercial diets on growth and digestive physiology in guppies (Poecilia reticulata)

Response to Reviewer 2 Comments

Dear Reviewer,

Thank you very much for your valuable comments and questions. We have revised our manuscript according to your suggestions. Our responses are as follows:

Reviewer #2: The authors wrote clearly throughout the text, so this was not a difficult read overall. I understood everything that the study was about. My biggest request of the authors is that they pass this manuscript to a native English speaker with the mission of decreasing the use of so many commas and the unnecessary use of semi-colons. This is with the exception of the materials and methods, which I feel that the authors may have already passed this manuscript to a native English speaker because this section was written and structured perfectly in my opinion. 

We greatly appreciate your comments and suggestions, and we are reviewing the language of our work once again.

Reviewer #2: Other things to look out for:

-make sure you list your units for all numbers where necessary

We appreciate your observation, we have made the corrections

-make sure that you italicize the scientific names and "in vitro", among anywhere else that may be necessary.

We appreciate your observation, we have made the corrections.

-Remove the first sentence of the abstract, I do not think it is necessary

We followed your suggestion.

-Line 42, as an example: “The ornamental fish encompasses…”. Should this be ornamental fish industry? Look out for things like this.

We appreciate your observation, we reviewed the whole document again.

Other than these points, it was a well written manuscript.

Thank you for your comment.

Reviewer #2: Comments on the Quality of English Language

If the authors take care of what I said, it would be a perfect manuscript. If they at least take care of the excess use of commas and use of semi-colons, it will still be a very good manuscript.

We sincerely thank you for your comment.

Reviewer 3 Report

Comments and Suggestions for Authors

The Authors of the study titled "Effect of commercial diets on growth and digestive physiology in guppies (Poecilia reticulata)" have presented a relatively basic research paper which aimed to expand the knowledge in the sparsely-studied field of ornamental fish nutrition. The experimental design and conducted analyses were not too complicated, but some interesting results were nonetheless obtained.

There are several problems which I have spotted within the M&M section, all of which require clarification. Most importantly, however, the Authors need to provide a clarification of their use of freezing in -20C as the sole method of fish euthanasia, as this is obviously a very important ethical issue.

On the other hand, the Discussion is actually very long, to the point of almost being excessive. However, it is not that big of an issue.

In the attached file the Authors may find all of my suggestions and questions, all of which must be answered in their revision. I especially advise to add panels of histological images of the liver and intestine of studied guppies.

In summary, the paper adds some new information to the relatively obscure field of ornamental fish husbandry, but it is not a groundbreaking study, unfortunately.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

In the attached file, I have spotted a few mistakes and suggested appropriate corrections. The text is generally understandable, although at times the quality of the English language does indeed appear to be varying, especially when the sentences become long and convoluted.

Author Response

Manuscript ID: aquacj-3651299  

Title: Effect of commercial diets on growth and digestive physiology in guppies (Poecilia reticulata)

Response to Reviewer 3 Comments

Dear Reviewer,

Thank you very much for your valuable comments and questions. We have revised our manuscript according to your suggestions. Our responses are as follows:

Reviewer #3: The Authors of the study titled "Effect of commercial diets on growth and digestive physiology in guppies (Poecilia reticulata)" have presented a relatively basic research paper which aimed to expand the knowledge in the sparsely-studied field of ornamental fish nutrition. The experimental design and conducted analyses were not too complicated, but some interesting results were nonetheless obtained. There are several problems which I have spotted within the M&M section, all of which require clarification. Most importantly, however, the Authors need to provide a clarification of their use of freezing in -20C as the sole method of fish euthanasia, as this is obviously a very important ethical issue.

Thank you for your comment and we regret the confusion, the organisms were first placed in a concentration of clove oil (1 mL L-1) and then placed in a cold temperature shock, due to the size of the organisms (<0.15 g) this process was almost instantaneous (less than 5 seconds), in the same way during the experiment and the sacrifice of the organisms the protocols of the Declaration of Helsinki and the protocol authorized by the Ministry of Agriculture, Livestock, Rural Development, Fisheries and Food (SAGARPA), of the government of Mexico, NOM-062-Z00-1999 were followed. Finally, the development of this experiment had the approval (UJAT-CIEI-2025-059) of the Institutional Commission of Ethics in Research of the Academic Division of Biological Sciences of the Juárez Autonomous University of Tabasco, Mexico. Likewise, the M&M section was rewritten detailing the process step by step.

Reviewer #3: On the other hand, the Discussion is actually very long, to the point of almost being excessive. However, it is not that big of an issue.

Thank you for your comment. We have evaluated the information and improved this section.

Reviewer #3: In the attached file the Authors may find all of my suggestions and questions, all of which must be answered in their revision. I especially advise to add panels of histological images of the liver and intestine of studied guppies.

Thank you for your comments and suggestions. We analyzed all of them; the adjustments are noted in the text. Regarding the histological analysis, we agree with you and have added a new figure representing our results.

Reviewer #3: In summary, the paper adds some new information to the relatively obscure field of ornamental fish husbandry, but it is not a groundbreaking study, unfortunately. In the attached file, I have spotted a few mistakes and suggested appropriate corrections. The text is generally understandable, although at times the quality of the English language does indeed appear to be varying, especially when the sentences become long and convoluted.

Thank you for your comments. We followed your suggestions, highlighted in blue. We also reviewed the language throughout the document.

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The Authors have successfully incorporated all of my previous suggestions and have solved the most important issue, which pertained the euthanasia process. The manuscript is now suitable for publication.

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