- Freshwater Shrimp
Shrimp are decapods or 10 limbed crustaceans along with crayfish, cherax crabs and others. Historically only really crayfish were kept, in the last 10-15 years shrimp and other crustaceans have become increasingly popular in home aquaria. This article will try to give an overview on owning, keeping and breeding of the dwarf freshwater shrimp, fan handed shrimp and longarmed shrimp as well as the dwarf crayfish. Although not precise the term "shrimp" will be primarily used to cover all of these. Because of the wide number of decapods being covered generalisations will occur and more specific details should be sought once a choice of inhabitant has been chosen.
The different types of Decapods covered include:
1. The algae eaters mainly from the neocardina and cardinia species: these are collectively referred to as the dwarf shrimp.
2. Long-armed or macrobrachium which are opportunistic hunters and so have different requirements as far as tank mates and raising of young.
3. The fan shrimp or atya, atyoides and atyoida species which can be quite large and are generally peaceful, should generally be housed in groups. They are named after the specialised adaptations to their first appendages which have developed to sieve the water and fan particles toward there mouths. they need good circulation and suspended bacteria/microorganisms to feed on often near a filter return or perched on some ornament.
4. Dwarf crayfish (need to check legality of english keeping) which are as they say smaller peaceful version of their larger cousins. Most of this group come from the Cambarellus group. Procambarus crayfish are much larger.
A species-only tank is best, unfortunately many new keepers wish to have them as part of a community often because we have only one tank and want as much variety and interest as possible. The shrimp suffer and often hide from the fish in this type of situation, depriving us of the most enjoyment and depriving the shrimp of the most suitable habitat. With the long armed shrimp being predators and often consuming protein, other fish, shrimps and even snails will be taken at times dependant on the particular species. Again a species only tank is therefore best for separate reasons with these. The dwarf crayfish although generally peaceful, can even be harmful to each other with males to male aggression being more likely and again is most suited to a species only tank. There will always be reports of successfully keeping varied combinations of shrimp, crayfish, fish, etc. and it is not for me to say that these combinations will not work in individual situations. It is important just bear in mind the basic guidelines and decide what is more important to you which is hopefully your inhabitants health and welfare.
For the majority of shrimp a neutral and medium hardness water is generally suitable. Some species of shrimp do have preference's for slightly acidic or moderately alkaline waters though a range of 6.5 to 7.5 pH and hardness levels around 10 gH are adequate starting points in most case's. Once deciding on a specific species it would be advisable to research further it's exact water requirements. You can easily check the species requirements for shrimp and crayfish by visiting each respective species information page. Check out the Shrimp Species Page and Crayfish Species Page for a list of all species.
When changing water it is important to try and match the new water with the old water in respect to temperature and hardness or tds readings. I find this more important with shrimp than with fish. Most important in water is ensuring that chlorine, chloramine and heavy metals are removed with dechlorinators prior to adding to the tank. With their increased sensitivity to heavy metals shrimp are more susceptible to leached ions from hot water systems in which water contact with copper pipes is longer. It is highly recommended not to use any hot tap water when performing water changes. If the water from the tap is too cold please read the article Changing Water in the Winter for detailed information on how to overcome the difficulty with changing water when the tap is too cold.
Compatible Tankmates for Shrimp:
There are some compatible tankmates for shrimp. Some other species of shrimp, fish with specialised feeding mouths i.e. otocinclus cory's and ancistrus or other small plecs and some of the specialised surface feeding fish. Any larger fish will frighten shrimp whether predating or not. Obviously depending on what you initially want and size of tank, choices may vary from many varieties of dwarf shrimp with the biggest concern being cross breeding of the various species to breeding tanks of dwarf crayfish in which only females maybe held with the male introduced for short breeding periods. Please read the article Will These Shrimp Interbreed for more information on possible interbreeding and hybridization.
Most aquarium shrimp strains are chosen for there high coloration. This is an exaggerated trait that reduces the shrimps camouflage abilities and tends to make them more interesting to most fish. I can not stress enough the importance of not keeping fish and shrimp together. Basically any fish that can fit a shrimp in it's mouth will most likely eat a shrimp. Once fish associate the shrimp with food they will quickly hunt down all shrimp in a tank, the exceptions previously listed are not inclined to do this and exceptions exist to almost any rule. Please read the article Safe Tankmates for Shrimp for more information on potential tankmates.
If you intend to breed shrimp then no fish is best as baby shrimp are so small that they will inevitably be eaten by even the most mild mannered of fish. Just think baby brine shrimp are one of the most popular foods for fish breeders. Even shrimp will consume dead and sick cohabitants , small dwarf crayfish have been recorded to predate dwarf shrimp and it goes without saying that the longarmed shrimp will predate or pick off small sick and sleeping fish and shrimps.
Dwarf shrimp often can be sexed by body shape(females have extended what are the shell pieces (pleura) called on the tail region for assisting in carriage of egg's, males are slimmer and prehaps less coloured. Males will often have longer antennae- more pronounced on the second smaller pair of antennae. Though in certain species this is not so easy and the most correct biological way is to actually look for the genital openings beneath the shrimps the female opening is located on the 6th body segement whilst the males is between the 6th and 8th (not much use ina 2-3cm shrimp i know).
In macrobrachium the size of the clawed first appendage is usally the easiest way to tell male from female with males having the larger claws, commonly there is a signifcant body size difference in fully grown specimens as well.
Fan handed shrimp tend to have larger first walking leg's in male shrimp and the extension of the carapace or pleura ventrally to assist in egg carriage.
In the dwarf crayfish external genital differences are visible beneath the tail where the first pleopod shows specialised adaptions.
Of interest is the recording of partial hermaphroditic changes in most decapods and certainly the farmed interest in single sex (males grow faster and thought to be economically more profitale) rearing via androgenic hormone manipulation.
Two different ways all shrimp produce egg's in the ovaries which can often be seen developing through the shell on the back and just behind the head, at moulting these egg's. If mating has occurred the unfertilized eggs pass down and through the genital opening (where sperm has been deposited at mating) to be fertilised and held on the swimmerrettes or pleopods under the tail of the female.
Most dwarf shrimp take about 3-4 weeks for these egg's to hatch, if you see a shrimp carrying egg's under the tail they are almost always fertilised. 1. Some shrimp produce fully developed miniature versions of adult shrimp 2. Others produce a planktonic life stage (zoea) which is free floating and swimming. This planktonic breeding cycle requires an increase in salinity and smaller suspended particulate foods to develop to the juvenile stage.
By Andrew Pollock