The article is very interesting and of great importance for the optimization of the rearing in the nursery phase of the species used. I think it should be published but some points need to be reviewed like an error of the animal size units in the discussion, improvements in the description of the methodology and if the authors have the information about the temperature, salinity or other water quality parameters in the two locations they should insert them to improve the work and allow a better discussion regarding growth and survival.
In more detail here are some points that should be reviewed:
In the introduction some more information about the feeding habits of the species in aquaculture and the methods commonly used in the nursery should be inserted to better understand throughout the work what are considered the competing species because the same feeding habits.
Page 5, Line 54 – insert the formula of AGR
Page 5 – In the experimental design section the authors should insert the information about feeding the sandfish. In the discussion the authors talk about high abundance of food (page 9 line 28) but in the methodology it is not mentioned which food is provided nor the amount and frequency of feeding. Or is no food provided? It should be mentioned here. The relationship between the exchange of nets and feeding is not clear in the discussion and it is here in the methodology that it should be mentioned, were the nets matured to have food inscrusted in them? What was the procedure? are the hapas placed first, how long before? And the net that is exchanged is placed to mature to have food already? This information must be included in the methodology.
Page 6 line 17 - The authors mention what they consider to be competitors or predators and identify the competitors as having the same feeding habits as the sea cucumber but never mention the feeding habit or diet to sandfish juveniles. This information should be insert here, the author can use some references and the information of feeding habits and how this species is fed in nurseries should also be included in the introduction.
Page 6 line 57 - This description of the number of species per family does not seem to me the most interesting to describe the results obtained. It would be better to have information about the number of competitor and predator species, talking about their feeding habits.
Table 1 – In the feeding habitat column there should be some references for each species.
The legend of this table should be more complete and the scientific name of the sandfish should be inserted and in full.
Table 2 – Insert units in the length (line3) and the scientific name of the sea cucumber, insert % in survival (Line 10)

Were some water quality parameters such as temperature, dissolved oxygen and salinity measured? These parameters may be related to the differences found in the survival and growth of sea cucumbers. It would be important to insert in the methodology what water quality parameters were measured so the authors can improve the discussion with the comparasion of these data and survival and growth in the two sites.
Page 10 line 3 - What is the relationship between changing the nets and the availability of food, does changing the nets once during the experiment indicate that food may be scarce - why? This part is not clear. Are the nets previously "matured"?
Page 10 – line 38. The size of the sandfish is not right, here it is in cm but in the rest of the work it is in mm. This way the sentence must be revised because it no longer makes sense.