Ectoparasites of Nile tilapia (<i>Oreochromis niloticus</i>) in cage farming in a hydroelectric reservoir in Brazil

Zago, Aline Cristina; Franceschini, Lidiane; Garcia, Fabiana; Schalch, Sérgio Henrique Canello; Gozi, Kátia Suemi; Silva, Reinaldo José da

doi:10.1590/S1984-29612014041

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Original Article • Rev. Bras. Parasitol. Vet. 23 (2) • Apr-Jun 2014 • https://doi.org/10.1590/S1984-29612014041 copy

Ectoparasites of Nile tilapia (Oreochromis niloticus) in cage farming in a hydroelectric reservoir in Brazil

Ectoparasitas de tilápias-do-Nilo (Oreochromis niloticus) criadas em tanques-rede em um reservatório de usina hidrelétrica no Brasil

Authorship SCIMAGO INSTITUTIONS RANKINGS

For this study, we performed a parasitological analysis of cage-cultured Nile tilapia (Oreochromis niloticus) from the Água Vermelha Reservoir, Southeastern Brazil, and verified relationships with limnological data, seasonality, and fish growth phase. From March 2010 to March 2011, sixty-three specimens of O. niloticusin three growth phases (i.e., initial, intermediate, and final) were collected. All fish specimens were infested with at least one ectoparasite species (prevalence = 100%). Five species of protozoans (Trichodina compacta, Trichodina magna, Ichthyophthirius multifiliis,Piscinoodinium pillulare, and Epistylissp.) and five species of monogenoids (Cichlidogyrus halli, Cichlidogyrus thurstonae,Cichlidogyrus sp. 1, Scutogyrus longicornis, and Gyrodactylus sp.) were observed. The abundance of Trichodina spp. and the prevalence of Epistylis sp. were higher in the dry season, and the prevalence of C. halli was higher in the rainy season. For the majority of ectoparasites found in this study, fish in the intermediate and final phases had higher parasitism rates than those in the initial phase. The data presented may help fish farmers to understand the parasite dynamics of the fish species studied in cage-farming systems.

Fish farming; health; water quality; monogenoid; Trichodina spp.; Ichthyophthirius multifiliis

Ectoparasites	Dominance frequency	Mean relative dominance^* * Values presented as mean ± standard error (range).
Trichodina spp.	45	0.6 ± 0.3
Ichthyophthirius multifiliis	0	0.01 ± 0.02
Cichlidogyrus halli	14	0.2 ± 0.3
Cichlidogyrus thurstonae	4	0.1 ± 0.2
Cichlidogyrus sp. 1	0	0.001 ± 0.1
Scutogyrus longicornis	0	0.03 ± 0.1
Gyrodactylus sp.	0	0.04 ± 0.1

Fish growth phase	Weight (g)	Standard length (cm)	P (%)	MII^* * Values presented as mean ± standard error (range). g: gram; cm: centimeter. Prevalence, mean intensity of infection and mean abundance followed by the same letter in the column: no significant difference (p > 0.05). Epistylis sp. was not included in the calculations of mean intensity of infection and mean abundance because it is a colonial protozoan.	MA^* * Values presented as mean ± standard error (range). g: gram; cm: centimeter. Prevalence, mean intensity of infection and mean abundance followed by the same letter in the column: no significant difference (p > 0.05). Epistylis sp. was not included in the calculations of mean intensity of infection and mean abundance because it is a colonial protozoan.
Initial	56.4 ± 13.7 (1.4-214.3)	10.06 ± 0.9 (4.2-17.2)	100^a	25 ± 5.9 (2-108)^a	25 ± 5.9 (2-108)^a
Intermediate	228.4 ± 27.4 (59.8-444.6)	18 ± 0.8 (13-23.5)	100^a	181 ± 94.3 (10-2030)^b	181 ± 94.3 (10-2030)^b
Final	590.6 ± 59.6 (205.4-1481.1)	24.2 ± 0.8 (17-32)	100^a	581.2 ± 387.6 (4-8199)^b	581.2 ± 387.6 (4-8199)^b

Ectoparasites	Prevalence (%)			Mean intensity of infection^* * Values presented as mean ± standard error (range).†The calculations of mean intensity of infection and mean abundance were not performed as this is a colonial protozoan. Prevalence, mean intensity of infection and mean abundance followed by the same letter in the row: no significant difference (p > 0.05).			Mean abundance^* * Values presented as mean ± standard error (range).†The calculations of mean intensity of infection and mean abundance were not performed as this is a colonial protozoan. Prevalence, mean intensity of infection and mean abundance followed by the same letter in the row: no significant difference (p > 0.05).
Ectoparasites	IN	IT	FN	IN	IT	FN	IN	IT	FN
Trichodina spp.	76.2^a	100^a	90.5^a	23.9 ± 7.1 (2-96)^a	159.3 ± 83 (2-1778)^b	603 ± 405.3 (2-7768)^b	18.2 ± 5.8 (0-96)^a	159.3 ± 83 (2-1778)^b	545.5 ± 367.9 (0-7768)^b
Ichthyophthirius multifiliis	0^a	9.5^a	38.1^b	0^a	100 ± 98 (2-198)^a	51.1 ± 1 (2-10)^a	0^a	9.5 ± 9.4 (0-198)^a	1.9 ± 0.7 (0-10)^a
Epistylissp.^†	19.1^a	52.4^a	57.14^a	-	-	-	-	-	-
Piscinoodinium pillulare	4.8^a	0^a	0^a	1^a	0^a	0^a	0.1 ± 0.1 (0-1)^a	0^a	0^a
Cichlidogyrus halli	61.9^a	100^a	90.5^a	5.3 ± 1.8 (0.7-23.5)^a	4.5 ± 0.7 (0.9-13.5)^a	7.2 ± 2.6 (0.6-45.5)^a	3.3 ± 1.2 (0-23.5)^a	4.5 ± 0.7 (0.9-13.5)^a	8 ± 2.4 (0-45.5)^b
Cichlidogyrus thurstonae	57.1^a	95.2^a	85.7^a	2.4 ± 0.9 (0.3-9.7)^a	4.7 ± 1.6 (0.3-25.5)^a	4.2 ± 0.7 (0.8-12.2)^a	1.4 ± 2.5 (0-9.7)^a	4.5 ± 1.4 (0-25.5)^a	4 ± 0.7 (0-12.2)^a
Cichlidogyrus sp. 1	0^a	0^a	61.9^b	0^a	0^a	0.2 ± 0.1 (0.01-1)^a	0^a	0^a	0.1 ± 0.1 (0-1)^a
Scutogyrus longicornis	42.9^a	85.7^a	76.2^a	0.3 ± 0.1 (0.1-1)^a	1.6 ± 0.4 (0.3-6)^b	1.7 ± 0.5 (0.1-8.2)^b	0.1 ± 0.1 (0-1)^a	1.4 ± 0.3 (0-6)^b	1.3 ± 0.4 (0-8.2)^b
Gyrodactylus sp.	33.3^a	33.3^a	47.6^a	5.7 ± 1.5 (2-12)^a	7 ± 3 (1-24)^a	44.2 ± 38.3 (1-388)^a	1.9 ± 0.8 (0-12)^a	2.3 ± 1.2 (0-24)^a	21.1 ± 18.4 (0-388)^a

Parameters	Sampling months
Parameters	Mar/10^* * Months belonging to the rainy season (Mar: March, Nov: November, Jan: January);	May/10^† † Months belonging to the dry season (May, Jul: July, Sept: September);	Jul/10^† † Months belonging to the dry season (May, Jul: July, Sept: September);	Sept/10^† † Months belonging to the dry season (May, Jul: July, Sept: September);	Nov/10^* * Months belonging to the rainy season (Mar: March, Nov: November, Jan: January);	Jan/11^* * Months belonging to the rainy season (Mar: March, Nov: November, Jan: January);	Mar/11^* * Months belonging to the rainy season (Mar: March, Nov: November, Jan: January);
Dissolved oxygen (mg.L^–1)	6.6	6.7	6.3	7.6	3.9	6.2	5.2
Transparency (m)	2	> 2	> 1.5	1.5	0.98	>1.5	> 1.5
pH	7	7	7	6.8	6.5	7.5	7
Temperature (°C)	29.3	24.5	22.9	23.6	28.6	30.8	28.6
Ammonia (mg.L^–1)	0.1	0	0	0.1	0.1	0.1	0.1
Toxic ammonia (mg.L^–1)	9 × 10^–4	0	0	6 × 10^–4	2.3 × 10^–4	2.3 × 10^–4	9 × 10^–4
Nitrite (mg.L^–1)	0.1	0.03	0	0	0.03	0.1	0.03
Rainfall (mm)^‡ ‡ Rainfall data were obtained by consulting the database CIIAGRO - Centro Integrado de Informações Agrometeorológicas of the São Paulo State, Brazil.	147.3	58.9	14.1	64.5	124	271.6	147.3

Ectoparasites	P (%)		MII^* * Values presented as mean ± standard error (range).		MA^* * Values presented as mean ± standard error (range).
Ectoparasites	DS^γ γ DS: dry season (April to September) -n = 36;	RS^λ λ RS: Rainy season (October to March) -n = 27.	DS^γ γ DS: dry season (April to September) -n = 36;	RS^λ λ RS: Rainy season (October to March) -n = 27.	DS^γ γ DS: dry season (April to September) -n = 36;	RS^λ λ RS: Rainy season (October to March) -n = 27.
Trichodina spp.	96.3^a	83.3^a	472.8 ± 302.5 (4-7768)^a	96.4 ± 33.8 (2-926)^a	455.3 ± 291.6 (4-7768)^a	80.3 ± 28.8 (0-926)^b
Ichthyophthirius multifiliis	28.6^a	11.1^a	37.7 ± 32.1 (2-198)^a	3.8 ± 1.2 (2-7)^a	8.4 ± 7.3 (0-198)^a	0.4 ± 0.2 (0-7)^a
Epistylis sp.^† γ DS: dry season (April to September) -n = 36;	71.4^a	33.3^b	-	-	-	-
Piscinoodinium pillulare	11.1^a	0^a	1^a	0^a	0.1 ± 0.1 (0-1)^a	0^a
Cichlidogyrus halli	70.4^a	94.4^b	5.1 ± 1.2 (0.7-18.8)^a	6.4 ± 1.6 (0.6-45.5)^a	3.6 ± 0.9 (0-18.8)^a	6.1 ± 1.5 (0-45.5)^a
Cichlidogyrus thurstonae	90.5^a	86.1^a	3.7 ± 0.8 (0.3-12.2)^a	4.1 ± 1 (0.3-24.5)^a	2.6 ± 0.7 (0-12.2)^a	3.5 ± 0.9 (0-24.5)^a
Cichlidogyrus sp. 1	18.5^a	22.2^a	0.4 ± 0.2 (0.03-1)^a	0.2 ± 0.1 (0.01-0.9)^a	0.1 ± 0.04 (0-1)^a	0.04 ± 0.03 (0-0.9)^a
Scutogyrus longicornis	59.3^a	75^a	1.7 ± 0.4 (0.02-6)^a	1.2 ± 1.6 (0.05-8.2)^a	1 ± 0.3 (0-6)^a	0.9 ± 0.3 (0-8.2)^a
Gyrodactylus sp.	48.2^a	30.6^a	36.3 ± 29.4 (2-388)^a	5.4 ± 1.6 (1-18)^a	17.5 ± 14.3 (0-388)^a	1.6 ± 0.6 (0-18)^a
Total	100^a	100^a	506.1 ± 322.4 (0-8166)^a	94. 2 ± 30.1 (2-943)^a	506.1 ± 322.4 (0-8166)^a	94.2 ± 30.1 (2-943)^a

Colégio Brasileiro de Parasitologia Veterinária FCAV/UNESP - Departamento de Patologia Veterinária, Via de acesso Prof. Paulo Donato Castellane s/n, Zona Rural, , 14884-900 Jaboticabal - SP, Brasil, Fone: (16) 3209-7100 RAMAL 7934 - Jaboticabal - SP - Brazil
E-mail: cbpv_rbpv.fcav@unesp.br

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[1] ^*Corresponding author: Aline Cristina Zago, Departamento de Parasitologia, Instituto de Biociências, Universidade Estadual Paulista – UNESP, Campus de Botucatu, Distrito de Rubião Junior, s/n, CEP 18618-970, Botucatu, SP, Brasile-mail: alinecristhina@yahoo.com.br