Onoma1
Member
Otocinclus are a fish that were recommended to me as part of a ‘clean up crew’ and seem to be one of the ‘must have’ fish for aquascapers. On searching through the web for more information about them I noticed the lack of scientific evidence on how to care for, breed or manage these fish.
I started to put together some rough notes to help me and though they may be of interest to others. My summary points are below followed by the evidence gathered so far. I am not a biologist (this is probably self-evident). I would welcome any corrections of views on my analysis.
How many species?
In 1997 Schaefer identified 13 species within the genus Otocinlcus. By 2017 Delapieve et., al. note that this had risen to 20 types of Otocinclus with a new related genus Leptotocinclus which contains two species:
1. Otocinclus affinis Steindachner, 1877;
2. Otocinclus arnoldi Regan, 1909;
3. Otocinclus batmani Lehmann, 2006;
4. Otocinclus bororo Schaefer, 1997;
5. Otocinclus caxarari Schaefer, 1997;
6. Otocinclus cocama Reis, 2004;
7. Otocinclus flexilis Cope, 1894;
8. Otocinclus hasemani Steindachner, 1915;
9. Otocinclus hoppei MirandaRibeiro, 1939;
10. Otocinclus huaorani Schaefer, 1997;
11. Otocinclus juruenae Ribeiro, Lehmann, 2016;
12. Otocinclus macrospilus Eigenmann, Allen, 1942;
13. Otocinclus mangaba Lehmann, Mayer, Reis, 2010;
14. Otocinclus mariae Fowler, 1940;
15. Otocinclus mimulus Axenrot, Kullander, 2003;
16. Otocinclus mura Schaefer, 1997;
17. Otocinclus tapirape Britto, Moreira, 2002;
18. Otocinclus vestitus Cope, 1872;
19. Otocinclus vittatus Regan, 1904;
20. Otocinclus xakriaba Schaefer, 1997.
The new genus Leptotocinclus contains the species Leptotocinclus madeirae, . and Leptotocinclus ctenistus. Leptotocinclus is from the Greek leptos, meaning fine, small, delicate, and Otocinclus, a genus of Hypoptopomatini. (Delapieve et., al.2017).
Schaefer (1997) notes that many species are differentiated only under close scrutiny.
Below is a picture of a Otocindlus mariae (a male and fb emale) taken from Schaefer (1997)
Below is a picture of Otocinclus macrospilus both of which are female but caught in different locations
Schaefer (1997) argues that a strong likelihood that patterns of small-scale regional species endemism (that they will be unique to a particular area )
Distribution
Otocinclus Vittatus seem to be one of the more common fish found within the Amazon Basin. I take from Claro-García et., al. (2013) that while Otocinclus vittatus weren’t as widely distributed as some other types of fish they were found in very large volumes.
Claro-García et., al. (2013) note that Otocinclus vittatus (20.4%) of fish caught. In their paper they also in indicate that of the two areas surveyed the fish weren’t found in rio Purus basin but were found in six of the fifteen sample sites in the rio Acre basin. The three species Serrapinnus gr. microdon, Otocinclus vittatus and Hemigrammus ocellifer had a high dominance in the igarapés A (92%) and Pato (68.6%), igarapé Mapinguari (60.2%) and igarapé C (65%) respectively.
ANJOS et., al (2018) The Juruá and Purus rivers, contribute significantly for exports, mainly of species of Callichthydae (Corydoras spp.) and Loricariidae (Otocinclus spp.).
Otocinclus tapirape are found in the headwater streams (HS), rivers (R) and headwater streams and rivers (HS/R) of the upper section of the Tocantins–Araguaia River basin (de Carvalho 2018)
Behaviour
Axenrot, and Kullander (2003) note the memetic relationship between Corydoras diphyes and Otocinclus mimulus. A similar memetic relationship was noted in planet catfish between Otocinclus flexilis and Corydoras paleatus https://www.planetcatfish.com/common/species.php?species_id=1350
Satora et., al., (2019) notes that Otocinclus affinis uses its stomach as a respiratory organ in essence becoming air breathing. They notes that it is supposed that this species uses respiratory stomach only during dry season, when severe competition for limited food resources takes place and there are periods of period of hypoxia.
Habitat
Delapieve et., al. note that there collecting localities for Leptotocinclus are blackwater creeks and small rivers with a sandy bottoms
Mas, Alvarenga and Scarabotti (2019) note that O. arnoldi avoid major channels
Schaefer (2017) note that they are “distributed throughout most of lowland tropical South America and are generally found in smaller-sized streams and along quiet, slow-moving margins of larger rivers. They are typically found in locations characterized by clear, well oxygenated water, moderate flow, and abundant structure provided in the form of emergent marginal macro- phytes, or more commonly, where broad-leaf grasses, such as Brachiaria purpurescens, grow along the stream bank and extend into the water”. (page 4)
Otocinclus Mimulus was collected by Axenrot, and Kullander. (2003) in small streams with turbid water, shadowed by dense forest. The bottom of the river was littered with leaf litter and tree branches. Submerse plants were found in quiet areas of the river.
Satora, (2019) notes Otocinclus affinis is found in “..small streams and quiet slow-flowing margin rivers”.
Feeding and Resilience
I understand from the paper written by Claro-García and colleagues the areas in which they live are under intense pressure from human activity and the authors speculate that the success of this fish in this area relates to their ability to exploration these environment: high reproductive capacity in different environments, resistance to environmental variations, presence of schools of fish or the effect of environmental changes caused by human activities.
Schaefer (1997) refers to them as herbivorous catfish and states provides three forms of evidence to substantiate this. The first two relate to long intestine is adaptive in maximizing the extraction of nutrients from grazed plant material and the second is the large, thick-walled stomachs that may contribute to mechanical grinding of plant tissues found in catfish. Finally, he/she states “I have never observed anything other than plant material in Otocinclus stomachs” (page 30).
Schaefer (1997) also notes that other loricariids are opportunist omnivores, known to feed on invertibrates and moribund fish flesh
Observation from aquarists points to a more omnivorous diet. Acclimatisation of Otocinclus flexilis, for example is facilitated by feeding frozen bloodworms https://www.aquaticrepublic.com/common/species.php?species_id=1350
Mention is made of Otocinclus eating macrophytes and aufwuchs. I could not find a recent paper which provides a definitive view on this.
Collection
Anjos et., al (2018) noted that in 2003 90% of exports from the State of Brazil consisted of the following fish: Paracheirodon axelrodi, Petitella georgiae, Otocinclus flexilis, Carnegiella strigata, Hyphessobrycon socolofi, Otocinclus affinis, Corydoras reticulatus, Corydoras agassizii, Corydoras schwartzi, Corydoras julii e Peckoltia vittata
In 2003 457735 Otocinclus flexilis and 331535 Otocinclus affinis were exported from this area at an average price .of 006 US Dollars per fish Anjos et., al (2018)
"According to Procolombia, in 2012 Colombia received approximately US $7 million a year in otocinclus exports. Their data also says that between January and November of 2013, along with data of the Ministry of Trade, Industry and Tourism and the National Administrative Department of Statistics, Colombia exported US $7.9 million in ornamental fish which was an increase of 7% compared to 2012. The main destinations for these exports were Hong Kong, United States, Taiwan, Japan, Germany and China." http://www.dicyt.com/news/ornamental-fish-to-be-genetically-studied-due-to-overexploitation
When are they mature and how can breeding be stimulated?
In 1997 Schafer noted “…no published behavioral or reproductive information is available.”(page 21)
He went on to argue that “ Aquarists who have successfully spawned various species of Otocinclus and Microlepidogaster have informed me of aspects of the courtship and reproductive behaviors. In the interspecific inter- actions prior to spawning, individual males embrace the female by coiling the trunk around that of the female” (page 21)
Periera and Suarez (2019) noted that in the wild maturity of Otocinclus Vittatus estimated was 18.7 mm for females and 20.1 mm with a variation of between 10.5 to 41.25 mm.
Interestingly Periera and Suarez (2019) noted that breeding behaviour correlated with water level but not rainfall. Pereira and Suarez note that their reproductive peaks coinciding with peak river flows and speculate that this may be a strategy to colonize floodplain habitats.
Extrapolating from this may suggest that techniques such as adding further RO water or colder water to simulate rainwater in the hope that this stimulates breeding (used with Tetras) possibly won’t work.
Mas, Alvarenga and Scarabotti (2019) O. arnoldi, showed reproductive activity in spring and summer.
“..most species showed a marked reproductive seasonality, with reproductive activity concentrated in the warmer months of the summer. This strong reproductive seasonality is consistent with other studies of loricariids … and is coherent with the wide seasonal variation in day length and temperature in this subtropical system.”
References
Axenrot, Thomas E., and Sven O. Kullander. (2003) Corydoras diphyes (Siluriformes: Callichthyidae) and Otocinclus mimulus (Siluriformes: Loricariidae), two new species of catfishes from Paraguay, a case of mimetic association. Ichthyological Exploration of Freshwaters 14.3 249-272.
Borzone Mas, D., Alvarenga, P.F. and Scarabotti, P.A., 2019. Ecological and phylogenetic determinants of life‐history patterns among Loricariidae. Journal of Fish Biology. (in press)
Claro-García A, Abrahão V, Vieira L, Jarduli L, Shibatta O (2013) Fishes (Osteichthyes: Actinopterygii) from igarapés of the rio Acre basin, Brazilian Amazon. Check List 9(6): 1410-1438.
Delapieve, M.L.S., Pablo Lehmann, A., Reis, R.E. (2017) An appraisal of the phylogenetic relationships of hypoptopomatini cascudinhos with description of two new genera and three new species (Siluriformes: Loricariidae) Neotropical Ichthyology, 15 (4)
de Carvalho, R.A. and Tejerina-Garro, F.L., 2018. Headwater–river gradient: trait-based approaches show functional dissimilarities among tropical fish assemblages. Marine and Freshwater Research, 69(4), pp.574-584.
dos ANJOS, H.D.B., de Souza AMORIM, R.M., SIQUEIRA, J.A. and dos ANJOS, C.R., 2018. Exportação de peixes ornamentais do estado do Amazonas, Bacia Amazônica, Brasil. Boletim do Instituto de Pesca, 35(2), pp.259-274.
PEREIRA, M. J. and SUAREZ, Y. R.. Reproductive ecology of Otocinclus vittatus (Regan, 1904) in the Pantanal floodplain, upper Paraguay River basin. Braz. J. Biol. [online]. 2019, vol.79, n.4 [cited 2019-10-04], pp.735-741. Available from: <http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1519-69842019000400735&lng=en&nrm=iso>. Epub Nov 23, 2018.
Satora, L., Kozioł, K., Waldman, W., & Mytych, J. (2019). Differential expression of epidermal growth factor receptor (EGFR) in stomach and diverticulum of Otocinclus affinis (Steindachner, 1877) as a potential element of the epithelium remodeling mechanism. Acta histochemica, 121(2), 151-155.
Schaefer, Scott A. (2017) “The Neotropical Cascudinhos: Systematics and Biogeography of the Otocinclus Catfishes (Siluriformes: Loricariidae).” Proceedings of the Academy of Natural Sciences of Philadelphia, vol. 148, pp. 1–120
I started to put together some rough notes to help me and though they may be of interest to others. My summary points are below followed by the evidence gathered so far. I am not a biologist (this is probably self-evident). I would welcome any corrections of views on my analysis.
- 20 species currently identified. Many species are differentiated only under close scrutiny. There is a strong possibility of misclassification by non-expert.
- The latest figures that I could find indicated vast numbers of these fish being caught and exported. In 2003 457735 Otocinclus flexilis and 331535 Otocinclus affinis were exported from the Amazon Basin at an average price .of 006 US Dollars per fish. I noted that most for sale in the UK are currently Otocinclus affinis, although pictures of the fish for sale labelled affinis seemed to show a different species. This raises questions about overfishing and sustainability.
- There is a strong likelihood that patterns of small-scale regional species endemism (that they will be unique to a particular area) and adaptation to these local environments.
- They are found across the Amazon basin, however, are localised and found in very large volumes. The areas in which they live are under intense pressure from human activity.
- There is a mimetic relationship between Corydoras diphyes and Otocinclus mimulus and Otocinclus flexilis and Corydoras paleatus this may be a form of adaptation.
- They are diurnal.
- Otocinclus affinis uses its stomach as a respiratory organ with suggestions that this is a evolunatory adaption to allow survival in periods when food resources are reduced and there are periods of hypoxia – dry season when low oxygen levels in the water.
- The typical types of habitat are small rivers and streams, shaded blackwater, streams with turbidity, streams with clear highly oxygenated water. I found this slightly contradictory and assume the difference suggests seasonal variation in turbidity. It doesn't, however, suggest a densely planted environment.
- They are referred to as herbivores based on the physical structure of the intestine and stomach. Conclusions seem to have been drawn using dissection not observation of behaviour. It is noticeable that catfish with similar characteristics eat invertebrates and moribund fish flesh. My view on this that aquarists have observed them eating bloodworms and Repashy Soilent Green (containing insect protein). Acclimatisation of Otocinclus flexilis was facilitated by feeding frozen bloodworms. Therefore, either they are not pure herbivores or different species have different requirements. Equally, flexibility of eating habits has been noted as a potential rationale for their large numbers within environments under intense human pressure which have experienced significant changes.
- Little behaviour or reproductive information seems to be available. I noted that most of the papers seemed to deal with dissection and analysis of dead fish and extrapolating from this with only a few more recent papers focusing on behaviour. They rarely breed in captivity.
- The mature size of Otocinclus Vittatus varies but averaged at 18.7 mm for females and 20.1 mm with a variation of between 10.5 to 41.25 mm. Breeding behaviour correlated with peak river flows but not rainfall. Extrapolating from this may suggest that techniques such as adding further RO water or colder water to simulate rainwater in the hope that this stimulates breeding (used with Tetras) possibly won’t work.
- They show, marked reproductive seasonality therefore wide seasonal variation in day length and temperature may stimulate breeding behaviour.
How many species?
In 1997 Schaefer identified 13 species within the genus Otocinlcus. By 2017 Delapieve et., al. note that this had risen to 20 types of Otocinclus with a new related genus Leptotocinclus which contains two species:
1. Otocinclus affinis Steindachner, 1877;
2. Otocinclus arnoldi Regan, 1909;
3. Otocinclus batmani Lehmann, 2006;
4. Otocinclus bororo Schaefer, 1997;
5. Otocinclus caxarari Schaefer, 1997;
6. Otocinclus cocama Reis, 2004;
7. Otocinclus flexilis Cope, 1894;
8. Otocinclus hasemani Steindachner, 1915;
9. Otocinclus hoppei MirandaRibeiro, 1939;
10. Otocinclus huaorani Schaefer, 1997;
11. Otocinclus juruenae Ribeiro, Lehmann, 2016;
12. Otocinclus macrospilus Eigenmann, Allen, 1942;
13. Otocinclus mangaba Lehmann, Mayer, Reis, 2010;
14. Otocinclus mariae Fowler, 1940;
15. Otocinclus mimulus Axenrot, Kullander, 2003;
16. Otocinclus mura Schaefer, 1997;
17. Otocinclus tapirape Britto, Moreira, 2002;
18. Otocinclus vestitus Cope, 1872;
19. Otocinclus vittatus Regan, 1904;
20. Otocinclus xakriaba Schaefer, 1997.
The new genus Leptotocinclus contains the species Leptotocinclus madeirae, . and Leptotocinclus ctenistus. Leptotocinclus is from the Greek leptos, meaning fine, small, delicate, and Otocinclus, a genus of Hypoptopomatini. (Delapieve et., al.2017).
Schaefer (1997) notes that many species are differentiated only under close scrutiny.
Below is a picture of a Otocindlus mariae (a male and fb emale) taken from Schaefer (1997)
Below is a picture of Otocinclus macrospilus both of which are female but caught in different locations
Schaefer (1997) argues that a strong likelihood that patterns of small-scale regional species endemism (that they will be unique to a particular area )
Distribution
Otocinclus Vittatus seem to be one of the more common fish found within the Amazon Basin. I take from Claro-García et., al. (2013) that while Otocinclus vittatus weren’t as widely distributed as some other types of fish they were found in very large volumes.
Claro-García et., al. (2013) note that Otocinclus vittatus (20.4%) of fish caught. In their paper they also in indicate that of the two areas surveyed the fish weren’t found in rio Purus basin but were found in six of the fifteen sample sites in the rio Acre basin. The three species Serrapinnus gr. microdon, Otocinclus vittatus and Hemigrammus ocellifer had a high dominance in the igarapés A (92%) and Pato (68.6%), igarapé Mapinguari (60.2%) and igarapé C (65%) respectively.
ANJOS et., al (2018) The Juruá and Purus rivers, contribute significantly for exports, mainly of species of Callichthydae (Corydoras spp.) and Loricariidae (Otocinclus spp.).
Otocinclus tapirape are found in the headwater streams (HS), rivers (R) and headwater streams and rivers (HS/R) of the upper section of the Tocantins–Araguaia River basin (de Carvalho 2018)
Behaviour
Axenrot, and Kullander (2003) note the memetic relationship between Corydoras diphyes and Otocinclus mimulus. A similar memetic relationship was noted in planet catfish between Otocinclus flexilis and Corydoras paleatus https://www.planetcatfish.com/common/species.php?species_id=1350
Satora et., al., (2019) notes that Otocinclus affinis uses its stomach as a respiratory organ in essence becoming air breathing. They notes that it is supposed that this species uses respiratory stomach only during dry season, when severe competition for limited food resources takes place and there are periods of period of hypoxia.
Habitat
Delapieve et., al. note that there collecting localities for Leptotocinclus are blackwater creeks and small rivers with a sandy bottoms
Mas, Alvarenga and Scarabotti (2019) note that O. arnoldi avoid major channels
Schaefer (2017) note that they are “distributed throughout most of lowland tropical South America and are generally found in smaller-sized streams and along quiet, slow-moving margins of larger rivers. They are typically found in locations characterized by clear, well oxygenated water, moderate flow, and abundant structure provided in the form of emergent marginal macro- phytes, or more commonly, where broad-leaf grasses, such as Brachiaria purpurescens, grow along the stream bank and extend into the water”. (page 4)
Otocinclus Mimulus was collected by Axenrot, and Kullander. (2003) in small streams with turbid water, shadowed by dense forest. The bottom of the river was littered with leaf litter and tree branches. Submerse plants were found in quiet areas of the river.
Satora, (2019) notes Otocinclus affinis is found in “..small streams and quiet slow-flowing margin rivers”.
Feeding and Resilience
I understand from the paper written by Claro-García and colleagues the areas in which they live are under intense pressure from human activity and the authors speculate that the success of this fish in this area relates to their ability to exploration these environment: high reproductive capacity in different environments, resistance to environmental variations, presence of schools of fish or the effect of environmental changes caused by human activities.
Schaefer (1997) refers to them as herbivorous catfish and states provides three forms of evidence to substantiate this. The first two relate to long intestine is adaptive in maximizing the extraction of nutrients from grazed plant material and the second is the large, thick-walled stomachs that may contribute to mechanical grinding of plant tissues found in catfish. Finally, he/she states “I have never observed anything other than plant material in Otocinclus stomachs” (page 30).
Schaefer (1997) also notes that other loricariids are opportunist omnivores, known to feed on invertibrates and moribund fish flesh
Observation from aquarists points to a more omnivorous diet. Acclimatisation of Otocinclus flexilis, for example is facilitated by feeding frozen bloodworms https://www.aquaticrepublic.com/common/species.php?species_id=1350
Mention is made of Otocinclus eating macrophytes and aufwuchs. I could not find a recent paper which provides a definitive view on this.
Collection
Anjos et., al (2018) noted that in 2003 90% of exports from the State of Brazil consisted of the following fish: Paracheirodon axelrodi, Petitella georgiae, Otocinclus flexilis, Carnegiella strigata, Hyphessobrycon socolofi, Otocinclus affinis, Corydoras reticulatus, Corydoras agassizii, Corydoras schwartzi, Corydoras julii e Peckoltia vittata
In 2003 457735 Otocinclus flexilis and 331535 Otocinclus affinis were exported from this area at an average price .of 006 US Dollars per fish Anjos et., al (2018)
"According to Procolombia, in 2012 Colombia received approximately US $7 million a year in otocinclus exports. Their data also says that between January and November of 2013, along with data of the Ministry of Trade, Industry and Tourism and the National Administrative Department of Statistics, Colombia exported US $7.9 million in ornamental fish which was an increase of 7% compared to 2012. The main destinations for these exports were Hong Kong, United States, Taiwan, Japan, Germany and China." http://www.dicyt.com/news/ornamental-fish-to-be-genetically-studied-due-to-overexploitation
When are they mature and how can breeding be stimulated?
In 1997 Schafer noted “…no published behavioral or reproductive information is available.”(page 21)
He went on to argue that “ Aquarists who have successfully spawned various species of Otocinclus and Microlepidogaster have informed me of aspects of the courtship and reproductive behaviors. In the interspecific inter- actions prior to spawning, individual males embrace the female by coiling the trunk around that of the female” (page 21)
Periera and Suarez (2019) noted that in the wild maturity of Otocinclus Vittatus estimated was 18.7 mm for females and 20.1 mm with a variation of between 10.5 to 41.25 mm.
Interestingly Periera and Suarez (2019) noted that breeding behaviour correlated with water level but not rainfall. Pereira and Suarez note that their reproductive peaks coinciding with peak river flows and speculate that this may be a strategy to colonize floodplain habitats.
Extrapolating from this may suggest that techniques such as adding further RO water or colder water to simulate rainwater in the hope that this stimulates breeding (used with Tetras) possibly won’t work.
Mas, Alvarenga and Scarabotti (2019) O. arnoldi, showed reproductive activity in spring and summer.
“..most species showed a marked reproductive seasonality, with reproductive activity concentrated in the warmer months of the summer. This strong reproductive seasonality is consistent with other studies of loricariids … and is coherent with the wide seasonal variation in day length and temperature in this subtropical system.”
References
Axenrot, Thomas E., and Sven O. Kullander. (2003) Corydoras diphyes (Siluriformes: Callichthyidae) and Otocinclus mimulus (Siluriformes: Loricariidae), two new species of catfishes from Paraguay, a case of mimetic association. Ichthyological Exploration of Freshwaters 14.3 249-272.
Borzone Mas, D., Alvarenga, P.F. and Scarabotti, P.A., 2019. Ecological and phylogenetic determinants of life‐history patterns among Loricariidae. Journal of Fish Biology. (in press)
Claro-García A, Abrahão V, Vieira L, Jarduli L, Shibatta O (2013) Fishes (Osteichthyes: Actinopterygii) from igarapés of the rio Acre basin, Brazilian Amazon. Check List 9(6): 1410-1438.
Delapieve, M.L.S., Pablo Lehmann, A., Reis, R.E. (2017) An appraisal of the phylogenetic relationships of hypoptopomatini cascudinhos with description of two new genera and three new species (Siluriformes: Loricariidae) Neotropical Ichthyology, 15 (4)
de Carvalho, R.A. and Tejerina-Garro, F.L., 2018. Headwater–river gradient: trait-based approaches show functional dissimilarities among tropical fish assemblages. Marine and Freshwater Research, 69(4), pp.574-584.
dos ANJOS, H.D.B., de Souza AMORIM, R.M., SIQUEIRA, J.A. and dos ANJOS, C.R., 2018. Exportação de peixes ornamentais do estado do Amazonas, Bacia Amazônica, Brasil. Boletim do Instituto de Pesca, 35(2), pp.259-274.
PEREIRA, M. J. and SUAREZ, Y. R.. Reproductive ecology of Otocinclus vittatus (Regan, 1904) in the Pantanal floodplain, upper Paraguay River basin. Braz. J. Biol. [online]. 2019, vol.79, n.4 [cited 2019-10-04], pp.735-741. Available from: <http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1519-69842019000400735&lng=en&nrm=iso>. Epub Nov 23, 2018.
Satora, L., Kozioł, K., Waldman, W., & Mytych, J. (2019). Differential expression of epidermal growth factor receptor (EGFR) in stomach and diverticulum of Otocinclus affinis (Steindachner, 1877) as a potential element of the epithelium remodeling mechanism. Acta histochemica, 121(2), 151-155.
Schaefer, Scott A. (2017) “The Neotropical Cascudinhos: Systematics and Biogeography of the Otocinclus Catfishes (Siluriformes: Loricariidae).” Proceedings of the Academy of Natural Sciences of Philadelphia, vol. 148, pp. 1–120
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