This species is one of the more commonly-encountered botiids in the hobby and is also sold as 'blue', 'orange-finned', or 'red-finned' botia/loach. It's sometimes subject to artificial colouring with bright blue or purple dyes and we strongly recommend you do not purchase such fish (they're illegal in several countries).
Not only is there a welfare issue to consider but also the fact that the health of the fish is normally compromised during the process leaving them less vigorous and more susceptible to disease. The dyed fish are normally sold as 'blueberry' or 'raspberry' loach/botia.
It's sometimes confused with Y. lecontei though in reality the two are readily distinguishable from one another by body shape since Y. modesta is a deeper-bodied, more compact fish.
Further, in Y. lecontei the overall body colouration is usually brownish with a gold/green sheen and the dark markings present on either side of the caudal peduncle tend to be roundish and not meet on the ventral surface of the fish whereas in Y. modesta base body colour is most often bluish with blue/green sheen and when present (it isn't always) the dark caudal peduncle markings tend to form a continuous bar around the entire peduncle.
There exist both red and yellow-finned colour variants, with the latter sometimes referred to as Y. sp. 'blue fin' or, incorrectly, Y. lecontei. The former name is derived from the fact that the dorsal fin is the same colour as the body rather than the caudal fin, unlike in the red-finned form where both caudal and dorsal fins are the same colour, which has led to speculation it may represent an undescribed species.
Apparently both can be found living alongside one another in nature, but the red-finned form is predominant in the Mekong drainage and yellow-finned the Chao Phraya. At time of writing both are considered to be Y. modesta.
The genus Yasuhikotakia was erected by Nalbant (2002) to include some former members of Botia which were previously referred to as the Botia modesta 'group' following Taki (1972).
Members are defined by the following combination of characters as given by Kottelat (2004): mental lobe not developed in a barbel, with a pair of fleshy papillae at its anterior edge; fronto-parietal fontanelle large and wide; anterior chamber of gas bladder partly covered by bony capsule; posterior chamber large; top of supraethmoid narrow; optic foramen small; anterior process of premaxilla entire, not surrounding a cavity; rostral process long, with a more or less distinct ridge along inner edge; suborbital spine strongly curved backwards and bifid; head naked.
The family Botiidae has been widely considered a genetically distinct grouping since Nalbant (2002), having previously been considered a subfamily (Botiinae) of the family Cobitidae. Nalbant also moved some previous members of Botia into the new genus Yasuhikotakia based on a number of morphological characters.
Later Kottelat (2004) made further modifications to the taxonomy, raising Chromobotia for B. macracanthus and confirming that species previously included in the genus Hymenophysa should instead be referred to Syncrossus.
The former alteration was based on colour pattern plus some morphological characters and the latter because Hymenophysa not only represents a spelling mistake (McClelland's original spelling was Hymenphysa) but is a junior synonym of Botia.
More recently Kottelat (2012) erected the genus Ambastaia to accommodate A.nigrolineata and A. sidthimunki, two former members of both Botia and Yasuhikotakia.
As a result of these works the family Botiidae is thus divided into two tribes within which Botia appears to be the most basal lineage:
Tribe Leptobotiini - Leptobotia, Parabotia, Sinibotia.
Tribe Botiini - Ambastaia, Botia, Chromobotia, Syncrossus, Yasuhikotakia.
Phylogenetic studies by Tang et al. (2005) and Šlechtová et al. (2006) have largely confirmed this system to be correct although the latter disagreed with the placement of Sinibotia, finding it to be more closely related to the tribe Botiini.
Ambastaia nigrolineata and A. sidthimunki were found to be more closely-related to both Sinibotia and Syncrossus than Yasuhikotakia, despite being considered members of the latter at the time. Šlechtová et al. also proposed the use of subfamily names under the following system:
Subfamily Leptobotiinae - Leptobotia, Parabotia.
Subfamily Botiinae - Botia, Chromobotia, Sinibotia, Syncrossus, Yasuhikotakia.
Within these Botia appears to be the basal, i.e., most ancient, lineage and in a more-detailed phylogenetic analysis Šlechtová et al. (2007) confirmed the validity of the family Botiidae with the genera listed above as members rather then being grouped into subfamilies. This more recent, simpler system is the one we currently follow here on SF.
Some behavioural routines exhibited by Yasuhikotakia spp. have been recorded often enough that they've been assigned non-scientific terms for ease of reference.
For example during dominance battles (these occur most frequently when the fish have been introduced to a new tank, or new individuals added to an existing group) the protagonists normally lose much of their body patterning and colouration, a phenomenon that's come to be known as 'greying out'.
Such displays will sometimes also happen within an established group as individuals seek to improve social ranking but are usually nothing to worry about.
Interestingly some observations suggest that the character of the highest-ranked, or alpha, fish appears to affect that of the whole group though it must be said that scientific studies of botiid loach behaviour are virtually non-existent.
It certainly seems that they display a degree of 'personality' with some specimens being naturally bolder or more aggressive than others, for example. The alpha is normally the largest specimen within the group and often female.
'Shadowing' is an interesting behaviour in which younger individuals swim flank-to-flank with older, mimicking their every movement. Some keepers report that more than one smaller fish may shadow a larger simultaneously, with even three or four on each side!
The reason for it is unknown; it may relate to a group staying in touch with one another when rivers swell during times of flooding, perhaps reducing drag by swimming 'in formation' or having some other communicative function.
It's been observed in aquaria with both high and low water flow and seems to be habitual to the extent whereby some individuals will shadow other fishes if no conspecifics are present.
Sound also appears to be an important factor in communication since these loaches are able to produce audible clicking sounds, these increasing in volume when the fish are excited. The behavioural aspects of this phenomenon remain largely unstudied but the sounds are thought to be produced by grinding of the pharyngeal (throat) teeth or subocular spines.
A further curiosity is the so-called 'loachy dance' which involves an entire group swimming in a constant, restless fashion around the sides of the tank, usually utilising the full length and height.
The reasons for this are unknown and reports as to when it occurs vary but the most common triggers appear to be the addition of food, fresh water or new conspecifics, and it can last anything from a few minutes to a day or more.
Botiids also often settle at peculiar angles, wedged vertically or sideways between items of décor, or even lying flat on the substrate. This is no cause for alarm and appears to be a natural resting behaviour.
Yasuhikotakia spp. also possess sharp, motile, sub-ocular spines which are normally concealed within a pouch of skin but erected when an individual is stressed, e.g., if removed from the water. Care is therefore necessary as these can become entangled in aquarium nets and those of larger specimens can break human skin.
Botiids are also susceptible to a condition commonly referred to as 'skinny disease' and characterised by a loss of weight. This is especially common in newly-imported specimens and is thought to be caused by a species of the flagellate genus Spironucleus.
It's treatable although the recommended medication varies depending on country. Hobbyists in the UK tend to use the antibiotic Levamisole and those in the United States Fenbendazole (aka Panacur).
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