Paratya from Australia
By: Dr. Benjamin Mos
Paratya are probably one of the most under-rated shrimp in Australia.The common names 'glass shrimp', 'ghost shrimp' and 'clear shrimp' don't do this group of shrimp justice. Nor does their widespread use as live food. This species complex (a group of closely related species that are currently described as a single species) is very suited to life in aquaria, tough, are good algae eaters, wide spread and easily collected, and yet breeding them will provide a challenge for the most hardcore of shrimp keepers.
Why are Paratya so awesome?
In a word, potential. Paratya have a huge amount of potential for breeding new variations, as algae eaters in aquascapes, as tough shrimp for beginners, as a brackish water specialist for biotopes, and much more.
Paratya come in a variety of colours (blue, green, clear, black, orange and even full red individuals) and patterns (dorsal stripes, 'tiger-stripe' patterns, speckles and blotches). There is very little known about whether their colouration can be controlled by diet, stress or other environmental factors, or whether line breeding could result in fixed colour variants, so there is great potential for breeders to work on fixing colours/patterns.
Current status of the taxonomy of Australian Paratya
The genus Paratya in Australia has an interesting taxonomic history. Paratya australiensis was first described by Kemp in 1917. In 1953, Riek proposed several new species and sub-species of Paratya. However in 1979, Williams and Smith reviewed the genus and declared all the Paratya from the east coast of Australia were a single species, P. australiensis. Recent phylogenetic analysis (comparisons of the DNA from individuals from different locations) suggests P. australiensis is probably a group of closely related species - a species complex (Baker et al., 2004; Cook et al., 2006; 2007; Hughes et al., 2003; Hurwood et al., 2003). Currently, Australian taxonomists are working to unravel the Australian Paratya species complex. It appears the 'species' we call P. australiensis will likely be broken up into between 9 and 11 new species. This work may also shed light on the relationships among Australian Paratya and Paratya found elsewhere in the Indo-Pacific. The fact that Paratya from Australia are a species complex has important implications for hobbyists in terms of breeding, hybridization and collecting, and these issues will be examined in detail later in this article.
Where are Paratya found?
Species from the genus Paratya are not limited to Australia. They are found through-out the western Pacific, with "a disjunct northern range in the North Pacific (Japan, Korea, Ryukyu Islands, Siberia) and South Pacific (Australia, New Zealand, New Caledonia, Lord Howe, Norfolk Island)" (Page et al. 2005). The Paratya species from New Caledonia (see Choy & Marquet, 2002) are very attractively coloured and appear in the hobby (see link below). Whilst this article focuses on the Paratya from Australia, the information on captive husbandry and breeding should be useful for species collected and kept elsewhere.
In Australia, Paratya are found all along the east coast of Australia, from the Atherton Tablelands near Cairns in the north to the east coast of Tasmania. They are also found further inland, through the Murray-Darling system.
Approximate distribution of Paratya species in Australia
In these areas, Paratya are found in creeks, rivers and estuaries, but also frequently in static water, such as dams. Juveniles and adults from south-eastern Australia are very tolerant of brackish water up to a salinity of around nearly full seawater (33ppt, Walsh and Mitchell, 1995). However, juveniles and adults also live quite happily (and breed) in freshwater 10's or 100's of kilometres from the nearest ocean (e.g. Hancock, 1998). This leaves almost infinite scope for using Paratya in biotope aquariums, from brackish tanks with sand, nerites and plants all the way through to freshwater tanks with leaf litter and rocks, but no plants.
Some freshwater habitat pictures from the Mid North Coast of New South Wales
Paratya do not appear in the western half of Australia, and 'glass shrimp' caught on the west coast near Perth are likely to be a entirely different shrimp, Palaemonetes australis, although there have been reports of an introduction of Caridina indistincta from eastern Australia into several rivers near Perth (see link below). This is a good reminder why it is important never to release any aquarium organism, including shrimp, into the wild.
Also see paper by Harris et al. 2017
How do I know if I have Paratya?
I've realised whilst researching for this article that identification of Australian 'glass shrimp' is no where near as straight forward as what I had initially thought. Paratya can be easily confused with other native shrimp kept in aquaria, and it doesn't help that they have been mistakenly called 'cherry shrimp' in the past.
Two types of shrimp that are really easy to confuse with Paratya are juvenile Macrobrachium spp. and Caridina, particularly species from a group of shrimp currently known as Caridina indistincta. Caridina and Macrobrachium species are found alongside Paratya in the same habitats. In NSW Australia, you will often catch all three types at once!
How to tell Paratya apart from Macrobrachium?
Many of the pictures on the internet which are labelled Paratya are actually Macrobrachium spp., including adults which are at least three times larger than any reported size for Paratya. The mistake is easy to spot if you know what to look for.
To rule out if your shrimp is a juvenile macro, here is what to look for.
If it has 'arms', its a Macro!
Paratya have 10 legs roughly the same length
Macrobrachium spp. have 8 legs roughly the same length and 2 legs much longer (in technical terms, the second pair of pereiopods are very enlarged). In juvenile Macrobrachium, the longer legs are clear rather than black, but are still obviously longer.
How to tell Paratya apart from Caridina?
NOTE: If you have collected your shrimp from Victoria or South Australia, they are almost certainly one of the Paratya species and not a Caridina. The number of species of Caridina shrimp generally decrease from northern to southern Australia, and have not been found south of around the Shoalhaven River in New South Wales. If do you find a Caridina south of this region, please contact me as I'd be very interested to see it!
Once you've seen Paratya alongside many of the shrimp from the genus Caridina, they are fairly easy to tell apart given differences in their body shape and size, size of the rostrum, egg size, and sometimes coloration and patterning on the body.
For example, one of the closest shrimp in looks to Paratya is Caridina longirostris, but their small Australian distribution in northern Queensland means they aren't likely to be collected by most people and they aren't widespread in the hobby. Note that there is also a species of Caridina (undescribed) from the Northern Territory that looks almost identical to Caridina longirostris - the Darwin Algae Eater (DAE) or Caridina sp. NT nilotica. This species is more widespread in the hobby because it is farmed in the NT and made available to the bobby via a well known supplier.
Caridina longirostris - Note the large body size, very small green eggs, long rostrum and red striations. Together these characteristics can help differentiate this species from Paratya without the need to examine specimens under the microscope.
If you want to be doubly sure about what shrimp you have, then use the method below for distinguishing Paratya apart from any Caridina.
According to the taxonomic key by Choy and Horwitz (1995), there are two characteristics that distinguish 'P. australiensis' from all Australian Caridina shrimp; the presence of supra-orbital spines and the presence of exopods on all the pereiopods.
Now you are thinking 'what the hell does that mean?' and 'where the hell can I find those things on the shrimp?'
1. Supraorbital basically means 'behind the eyes'. So supraorbital spines are spines that are found behind the eyes. Paratya are the only small freshwater Australian shrimp that have these spines (Choy and Horwitz, 1995; Williams and Smith, 1979), so if your shrimp have these, well done you have a solid ID. All species of Caridina, including indistincta, do not have supraorbital spines.
Here is what the supraorbital spines look like.
2. Like all shrimp, Paratya have five pairs of legs (10 in total), plus some maxillipeds (arms) around the mouth to assist when feeding. The legs are called pereiopods and are used for walking around and picking up food, ect.
Exopods are basically little 'legs' that are attached to the pereiopods (or the main legs).
Paratya have an exopod on every pereiopod (Williams and Smith, 1979). In C. indistincta and other Caridina, exopods are absent or, in rare cases, found only on the first pair of pereiopods.
In the picture below, red is the exopods, blue is the pereiopods. Yellow is the third pair of maxillipeds (there are two pairs closer to the mouth that cant be seen here). You'll also notice that the front two pairs of pereiopods have chelae ('fingers' or 'pincers'). These are used during feeding to grab food. In fact, Paratya have been recorded using these to filter-feed like the Australian riffle shrimp, Australatya striolata (Gemmell, 1978).
And just to further confirm that the pictures are of a Paratya sp..
Here is the rostrum (nose). There are 9-36 spines on the dorsal (top) side of the rostrum and 0-11 on the ventral (bottom) side of the rostrum for 'P. australiensis'. The one in the pic has 30 dorsal and 11 ventral (yes, I counted them!). The number of spines is so variable because the number of spines increases as they grow (Williams and Smith,1979). C. indinstincta has only up to 8 spines on the ventral side of the rostrum (Riek, 1953).
And heres some pictures of the tail just because the colours look awesome.Notice there are both red and blue coloured spots.
Note also that the presence/absence of spines on and around the tail can be used to differentiate between different shrimp, particularly shrimp in the genus Caridina.
One thing you will have no doubt noticed is that both the supraorbital spines and the exopods are pretty small. The above pics were of a 35mm female, which is pretty much as big as 'P. australiensis' get (William and Smith, 1979), under a dissecting microscope (approx. 10 - 20 times zoom), and these features are still small. I could only just see the supraorbital spines with the naked eye in the right light at the right angle, and the exopods appeared only as a blur of movement above the legs. The point is that you will need some source of magnification to view these features.
Unfortunately not many people have access to a laboratory spec dissecting microscope, but luckily you don't need to! A lot of the point and shoot cameras available today have built in macro modes. Simply take a picture of your shrimp using the macro mode and zoom in on the photo if you need to. I often use my point-and-shoot camera in the field for getting quick IDs of shrimp, instead of using a portable dissecting microscope.
Here is one such photo - test yourself, is this a Paratya? (Answer at the end).
How to keep Paratya in aquaria?
So now you know you have Paratya. Now how should you go about keeping them?
The answer is easily. Paratya are hardy aquarium inhabitants, and tolerate a wide variety of pH, TDS and GH/KH, and some even tolerate high salinity - perfect for those with brackish set-ups. I've successfully kept Paratya in a variety of tanks including planted aquascapes with soft, acidic water conditions to a tank with small African cichlids with hard, high pH water conditions. In my experience, Paratya are peaceful and can be housed alongside pretty much any shrimp. Likewise they are happy alongside fish that are too small to consume them. Like most freshwater shrimp, Paratya live to around two years of age (Hancock and Bunn, 1997; Williams, 1977; Williams and Smith, 1979).
In general, the below water parameters should keep your Paratya happy and healthy.
Temperature: optimal 20-26*C, but will tolerate extremes 8-30*C in the wild.
Salinity: 0 - 33 ppt (nearly full seawater). Note Paratya is not found in brackish water in Queensland, but is found from 0- 33 ppt salinity in estuaries in Victoria (Kefford et al., 2004; Walsh and Mitchell, 1995).
pH: optimal at around 7.0 but handles 6.0 - 8.2.
TDS: not important as long as extremes are avoided
GH/KH: not important as long as extremes are avoided
Nitrate: Optimally as low as possible
Feeding Paratya is relatively straight forward as well. They will eat anything that any other shrimp eats, and additionally are good algae eaters. In the wild they have been recorded feeding on biofilms** (Burns and Walker, 2000; Moulton et al., 2012), particularly those that form on leaves (Schulze and Walker, 1997) and on aquatic freshwater plants, like Myriophyllum salsugineum (Piola et al., 2008). In fact, they have been kept alive and bred in the laboratory by being fed on pieces of Elodea that were covered by algae dominated biofilms (Hancock, 1998). Interestingly, these are one of the few shrimp to eat cyanobacteria (Burns and Walker, 2000; Piola et al., 2008), more commonly known as the dreaded Blue Green Algae (BGA), but I'm unaware of any instances where these have been used successfully to treat BGA in aquariums. My opinion is that they would likely go for other easy-to-access foods prior to eating BGA, but they may be useful in preventing BGA out-breaks.
**Note: An informative thread on biofilms (what they are and how they form) can be found here:
How to breed Paratya?
Now comes the tricky part of keeping these shrimp.
In the wild, breeding occurs in the warmer spring and summer months, and stops over winter (Hancock and Bunn, 1997; Richardson and Cook, 2006; Richardson et al., 2004; Williams and Smith, 1979). Breeding seems to be triggered by warmer temperatures and females will not become berried at low temperatures or after a temperature drop. Some females will breed twice within a season (Hancock and Bunn, 1997). It is certainly possible that breeding could occur in aquaria year round.
There is one important tip I can offer for shrimp keepers thinking of breeding these guys that could mean the difference between success and failure. In fact, this may apply to most, if not all, Australian native shrimp.
If you can, obtain 'headwater' shrimp to breed from.
What I mean by this is, try to collect your adults from areas that are well away from estuaries, as far inland as possible and better yet, above a natural block to upstream migration (like a waterfall). The reason for this is that shrimp collected from these areas will have a natural tendency to produce large eggs (Cook et al., 2007; Fawcett et al., 2010; Hancock, 1998; Hancock et al., 1998; Walsh, 1993). Why? Because larvae in these areas have to develop quickly before they are washed away downstream (e.g. over a waterfall).
Why are large eggs important for breeding in aquariums?
Because it means that:
- larvae from headwater adults are more likely to develop completely in freshwater
- larvae from headwater adults are likely to develop quickly before settling onto the substrate and feeding like adults. In contrast, low-land shrimp have longer larval stages and may need to be raised in brackish water to develop properly. This is especially true for larvae from adults found in brackish water.
- Headwater adults may even be a different species from lowland shrimp, and if so, will be adapted to living in pure freshwater and may even have direct-developing larvae (i.e. larvae that hatch out looking like mini adults instead of larvae that develop through a series of stages in the water column before settling onto the bottom as juveniles).
Therefore larvae from 'headwater' adults will be far easier to raise than larvae from adults collected from low-land areas. More in depth analysis of the topic of egg size in lowland and headwater shrimp can be found in Cook et al. (2007), Fawcett et al., (2010), Hancock (1998), Hancock et al.(1998) and Walsh (1993) but this literature is probably too in depth for the average aquarist.
Here are some examples of the difference that having headwater shrimp makes to breeding them:
Hancock (1998) used the following method to culture headwater 'P. australiensis':
- Berried females were collected from freshwater creeks and kept at 11, 18 and 21*C. Females were fed Elodea.
- Eggs kept at 11*C took 60 days to hatch, whilst those at 18 -21*C took 20-25 days.
- Once the eggs hatched, the larvae were fed with algae scraped from the walls of an aquarium kept outside. Water changes were made every two days (no filter mentioned).
- All the larvae kept at 11*C died, whilst those at 18 and 21*C developed normally.
- Larvae took between 15 and 28 days to develop before settling onto the bottom.
In contrast, Walsh 1993 used the following method to grow 'P. australiensis' collected from brackish estuaries:
- Adults were collected from 0.5 - 1.5 ppt salinity.
- Upon hatching, seawater was added to boost the salinity to 15ppt (within one hour). Larvae kept at salinity below 5ppt didn't survive. Survival was highest at 15ppt. Larvae hatched at night on approximately the 25th day from the females being berried.
- Larvae swam near the bottom with their tails pointing upwards
- Water was changed every 2-3 days
- Larvae were fed with newly hatched Artemia (Baby Brine Shrimp or BBS).
- Larval development took 28-45 days, by which time the larvae reach 4-5mm
- The larvae then settled onto the bottom and began feeding like adults.
Other authors (e.g. Hancock and Bunn, 1997) fed larvae using FPOM (Fine Particulate Organic Matter) which is organic matter less than 1mm in diameter. This ranges from microalgae and diatoms to decomposing plants, leaves and wood. With this in mind, powdered algae, like Spirulina, or finely ground shrimp food may make the perfect larval food.
There are also multiple online reports of successful breeding of P. australiensis in aquariums. However there is little variation in the methods used from those I have summarised above and often less detail, so I won't repeat them here.
One final thing with regards to breeding. It is very likely that many of the Paratya 'species' can interbreed. In fact a scientific paper recently published in the journal 'Journal of Heredity' by Wilson et al. (2016) describes such an event occurring in the wild due to an introduction of one Paratya type into a stream where they did not naturally occur.
This highlights the need for aquarists to be responsible with the shrimp they keep. Do not release any shrimp into the wild, even if you collected the shrimp from the same location previously.
I encourage everyone to try keeping and breeding these shrimp. They really deserve to be more highly considered than only as a live food.
Best of luck with your shrimp endeavors.
Baker, A. M., Hughes, J. M., Dean, J. C., & Bunn, S. E. (2004). Mitochondrial DNA reveals phylogenetic structuring and cryptic diversity in Australian freshwater macroinvertebrate assemblages. Marine and Freshwater Research, 55(6), 629-640.
Burns, A., & Walker, K. F. (2000). Biofilms as food for decapods (Atyidae, Palaemonidae) in the River Murray, South Australia. Hydrobiologia, 437(1-3), 83-90.
Cook, B. D., Baker, A. M., Page, T. J., Grant, S. C., Fawcett, J. H., Hurwood, D. A., & Hughes, J. M. (2006). Biogeographic history of an Australian freshwater shrimp, Paratya australiensis (Atyidae): the role life history transition in phylogeographic diversification. Molecular Ecology, 15(4), 1083-1093.
Cook, B. D., Bunn, S. E., & Hughes, J. M. (2007). A comparative analysis of population structuring and genetic diversity in sympatric lineages of freshwater shrimp (Atyidae: Paratya): concerted or independent responses to hydrographic factors?. Freshwater Biology, 52(11), 2156-2171.
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Hancock, M. A. (1998). The relationship between egg size and embryonic and larval development in the freshwater shrimp Paratya australiensis Kemp (Decapoda: Atyidae). Freshwater Biology, 39(4), 715-723.
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Answer to 'Is this a Paratya'? - No. This specimen does not have supra-orbital spines, and is in fact a species of Caridina, most likely in the nilotica complex.