Gas Bubble Disease.
This is a rare disease in aquariums, but nevertheless one that occurs, the so-called gas bubble disease. This disease is much more common in aquaculture and is associated with water supersaturation with atmospheric gases and oxygen. Gas bubble disease can occur in shrimp of any species or size. The disease is triggered by a rapid change in gas pressure in water, manifesting as air bubbles in the gills or “blisters” on the body surface.
Especially in shrimp tanks without aquarium equipment, where too many plants and algae grow, water supersaturation with oxygen can occur under the influence of intensive lighting. Plants convert carbon dioxide and release a lot of oxygen. This process is clearly visible by air bubbles that form on the surface of plants or algae and then, detaching, rise upwards (when bubbles appear, it means oxygen saturation is 100%). However, water with oxygen saturation reaching 250% becomes harmful. The animals’ blood becomes oxygenated to the exact same degree as the water.
But then the sun stops shining so brightly, and plants begin to produce less oxygen. Its amount in the water drops sharply — but not in the blood, where gas bubbles eventually form. These bubbles can clog blood vessels and lead to gas embolism (obstruction of blood vessels). Gradually, most of the bubbles accumulate in the blood vessels of the gills, resulting in the death of individual gill areas.
Excess nitrogen with a lack of oxygen can also be harmful and lead to gas bubble disease in shrimp. The main amount of nitrogen compounds enters the aquarium as fish food. Shrimp excrete nitrogen in the form of ammonia through the gills, and partially in the form of urea. If these toxic substances are not transformed in some way, they can accumulate in the water and thereby kill the animals.
The less oxygen in the aquarium water, the longer nitrification of toxic waste takes, and if they are not removed quickly enough, water supersaturation with nitrogen occurs. Thus, with excessive water saturation with nitrogen (more than 120%), shrimp can also develop gas bubble disease, with bubbles accumulating mainly under the shell, and ultimately these toxic substances can poison the shrimp.
Treatment methods: Treatment is possible in both described cases; for this, sick animals are placed in normal water or provided with good aeration using a compressor, thereby preventing excessive water saturation with gas bubbles. Regular water changes in shrimp tanks where aquarium equipment is not used will avoid the occurrence of this disease in shrimp. In addition, in tanks with a large number of plants, direct sunlight should be avoided.
“Porcelain” Disease.
“Porcelain” disease occurs only in newly imported shrimp. It has not yet been proven that this disease can occur in an established shrimp community or among newborn juveniles. The disease can appear in newly imported shrimp and arises due to transport stress and associated weakening of the immune system. The causative agent of “porcelain” disease is single-celled parasites called Microsporid Thelohania contejani, which live in the shrimp muscles.
These single-celled parasites affect the victim’s muscles, restricting its movement. Shrimp become sluggish up to complete numbness, leading to the death of the specimen. Affected specimens show symptoms of color loss and acquire a milk-white color on the head, which quickly spreads throughout the body. Limbs become hard and motionless. Then the specimen can only use its swimming legs. After a couple of hours, at most a day later, affected specimens lie motionless on their side. Specimens still try to swim, but cannot move forward and spin disoriented in circles in the water. At this point, they can only move their maxillipeds and then die.
Shrimp with such symptoms must be immediately removed from the aquarium, because due to cannibalism and eating by tankmates, healthy specimens can be infected. At an early stage, treatment with medications (medicated flakes) from Tetra, used in treating aquarium fish for Ichthyo, containing malachite green oxalate (benzoyl green), is used. It used to be and would still be an effective and easily obtainable remedy against this disease. But unfortunately, these medicated flakes are no longer produced, which complicates treatment. Malachite green oxalate (benzoyl green) can also be used in liquid form, contained in standard medications such as Exit, by soaking food flakes in them and then feeding them to the shrimp.
Milky Disease.
Milky disease proceeds somewhat differently compared to “porcelain” disease. In “porcelain” disease, white coloration of the head appears, which then spreads to the entire body, indicating that the specimen is infected with Myxosporidien. In milky disease, a milky color appears immediately across the entire body at the very beginning. Often, newly imported shrimp exhibit the phenomenon of a milky shell or milky coloration of the entire body. These symptoms usually occur in various species of glass shrimp and rhino shrimp. Specimens with such symptoms usually die within a very short time. Healthy specimens that eat dead sick specimens at night very soon acquire the same symptoms.
The disease is caused by Myxosporidien, which essentially devour shrimp from the inside. Myxosporidien are single-celled parasites that are also common in fish. They are very dangerous, and currently, there is no known effective treatment method. Treatment attempts using various types of penicillin from general (human) medicine slowed down the development of the disease but did not cure it. Moreover, this disease is transmitted only through cannibalism. Therefore, dead specimens and all specimens with such symptoms must be removed from the general aquarium to prevent further spread of the disease.
Muscle Necrosis.
Quite often, shrimp develop a white or milky color in the rear part, more precisely, in the muscle tissue. Such symptoms are also called muscle necrosis (tissue death). In biology, necrosis is understood as the process where individual or multiple cells are destroyed in a living organism. As a result, an inflammatory reaction or decomposition of surrounding tissues occurs. During cell decomposition, protein is released, thus producing a milky white coloration of the rear body part. Symptoms of muscle necrosis can be caused by the following reasons:
— Improper water composition: too high temperature, unsuitable pH, lack of oxygen.
— Bacterial infection.
— Myxosporidien (milky disease).
However, this can also be caused by changes in pH composition, pressure, lack of food and oxygen, stress, which under certain circumstances can lead to cell death. In species with a more or less transparent body, we can observe a change in the color of the muscle tissue; it becomes opaque, starting from the tail. This milky coloration usually begins in the tail area and over several days spreads towards the head until the entire rear part becomes white/milky in color. Daily large water changes often cure the disease. If this warning signal is ignored and necrosis has already spread across the entire abdomen, treatment becomes impossible, and the specimen dies within a few days.
Chronic Soft Shell Syndrome.
Causes: • Nutrient deficiency; • High substrate pH (> 6); • Low phosphate level in water (< 0.01 g/10 l); • Low organic matter content (< 7%); • Infrequent water changes; • Use of low-quality feeds.
External signs: Thin, soft shell for several weeks. The shell surface may be dark, uneven, and wrinkled. The shrimp themselves look weak. Do not confuse with the post-molt condition, when a clean, soft, and smooth shell hardens within 1-2 days. Affected shrimp grow poorly and eventually die. In addition, soft-shelled shrimp are susceptible to injuries, prone to cannibalism, and their shell surface becomes overgrown with Zoothamnium and other commensals.
Treatment: • use of high-quality feeds; • regular water changes, initially daily; • introduction of additional feeds, for example, mussel meat in the amount of 8-14% of the shrimp body weight daily for 2 weeks, or a diet containing calcium and phosphorus in a 1:1 ratio.
Protozoan Parasites.
An increase in the number of protozoa in the aquarium indicates poor water quality: pollution, organic overload, presence of bacteria in the water, low oxygen content. Protozoa also love elevated water temperatures in the aquarium. Most often, shrimp are troubled by protozoa such as Vorticella, Epistylis, Zoothamnium, Acineta, Ephelota, Microsporidia, and Gregarines. Distinguishing them and consequently diagnosing the disease can be done using microscopes.
Under unfavorable conditions (treatment, improved water quality, absence of bacteria, etc.), protozoa can transform into cysts: become rounded, cover themselves with a thick membrane, and lie low waiting for better times. Therefore, the main method of combating them is frequent water changes, which helps not only to get rid of excess organics they love, but also of themselves.
Temnocephala — small (0.8-14 mm) parasitic ciliate worms that lay eggs on the gills and carapace of crustaceans. Adults “roam” the host’s body, feeding on algae and other aquarium microfauna. They are easily recognized even without a microscope: tentacles on the anterior part and suckers on the posterior part are visible on their body.
Acineta — a species of protozoa from the suctorian ciliates, outwardly resembling an orchid flower. In the larval stage, these protozoa are free-swimming; in adulthood, they attach to the shrimp’s body using a stalk.
Methods of combating Vorticella, Epistylis, Temnocephala, and Acineta: • improving water quality, reducing organic and bacterial contamination through frequent water changes; • controlling crustacean stocking density; • improving nutrition; • When correcting maintenance conditions, getting rid of protozoa is possible due to molting.
Zoothamnium — protozoan ciliates that form entire colonies attached to the host’s body by a stalk. Somewhat resembling a small plant bush on a single stem or an umbrella turned inside out by the wind. Their size is 2-3 mm, so they can be seen with the naked eye. They feed on bacteria. They live both on plants, especially on Elodea (waterweed), and on crustaceans. They are dangerous because they affect the gills, making breathing difficult and causing suffocation.
Methods of combating Zoothamnium: • Formalin at a concentration of 50 ppm will help completely get rid of Zoothamnium without harming the shrimp.
Microsporidia — intracellular parasites. They have some affinity with fungi, but possess a distinctive feature unique only to them — an extrusion apparatus with which they pierce the host cell membrane and inject the germ into the cytoplasm. There are about 1,300 species of them, and depending on the species, they affect various organs in crustaceans: connective tissue, reproductive organs, nervous system, or muscles.
Infection usually begins with the telson (anal fin) or uropods (last pair of limbs) and moves forward. External signs of microsporidiosis manifest as the infected area acquiring a white, orange, or reddish color; sometimes blue-black spots appear on the back and sides, but a definitive diagnosis can only be made after examination under an electron microscope, as microsporidia are very small. Microsporidiosis is rare, but once it occurs, it can cause mass mortality of invertebrates.
Methods of combating Microsporidia: • Infected shrimp should be removed from the aquarium and destroyed by burning or boiling; • Disinfect aquarium equipment with products containing iodine or chlorine; • Boost shrimp immunity, including through probiotics.
Gregarines — endoparasites with anaerobic (oxygen-free) respiration inhabiting the intestines of freshwater invertebrates. Up to 0.5 mm in size. They use mollusks as an intermediate host. They infect shrimp of any age. Detected in the digestive tract under a microscope. They feed saprophytically, absorbing nutrients across their entire body surface. A large number of these protozoa interfere with particle filtration through the hepatopancreatic duct.
Methods of combating Gregarines: • Destruction of mollusks as intermediate hosts; • Boosting crustacean immunity through good nutrition and adding probiotics to the aquarium water.
False Fungus Disease.
Vorticellids belong to the type of ciliated protozoan microorganisms. Vorticellids, such as Epistylis spp., are causative agents of diseases arising from poor shrimp living conditions. Such diseases occur in organically “overloaded” bodies of water.
Symptoms: Since fungal infection symptoms are very similar to this disease, anti-fungal medications are often used and, of course, do not lead to a cure. Vorticellids occur in small colonies as a fluffy, gray-white fistula-like coating or as individual “rods” on the shell or head of mollusks. As a rule, vorticellids are harmless to shrimp, but only until they multiply in large numbers and get into the gills, leading to suffocation of the specimen. They attach on a spiral-shaped movable stalk at the bottom. Under certain conditions, vorticellids can detach from this stalk of one shrimp and move to other shrimp.
Treatment: The best way to treat Epistylis-type vorticellids is to improve water quality and perform an 80% water change for several days to reduce the bacterial density and their nutrient base. Additionally, medications containing malachite green oxalate (benzoyl green) should be used. For example, standard medications against Ichthyo such as Punktol or Exit (drug brand) are used. Alternatively, 0.37 grams of methylene blue and 0.37 grams of malachite green dissolved in 100 ml of 37% formalin can be used. It is applied at a dosage of 1.2 ml per 100 liters of aquarium water with additional application for several days.
Cotton Shrimp Disease (Sporozoen).
White nodules, convex growths, or oval, sometimes rod-shaped cysts in the head. These symptoms manifest in specimens such as Neocaridina denticulata and Neocaridina cf. zhangjiajiensis.
With such oval formations, which can be seen with the naked eye on the body of a white-pearly shrimp, we are talking about infection with spore capsules or cysts. These spores can range in size from microscopic to pinhead-sized. These capsules are caused by hundreds of microscopic parasites, with spores located close to each other but not connected. Depending on the species, these spores affect tissues and organs such as muscles, heart, reproductive organs, gills, nerves, and nerve ganglia. Mortality is low.
Since spores are heavier than water and sink to the bottom, they infect the specimen during feeding or when eating a victim, as well as when eating dead infected specimens (via cannibalism). Therefore, dead or sick specimens must be removed from the aquarium. However, spores can also enter a new host through the victim’s excrement. When a shrimp swallows spores during feeding, they enter the intestine in the form of an amoeba-like sprout. It penetrates through the intestinal wall into the musculature and forms new spores there with a cyst stage visible to the naked eye. In the late stage, spores penetrate internal organs and lead to degeneration and relaxation, resulting in the shrimp’s death.
Treatment: Medical treatment is currently unknown. One can only try to avoid new infections of healthy shrimp by removing sick specimens with visible signs or already infected specimens from the aquarium. Also, all dead specimens should be removed from the aquarium as quickly as possible to avoid cannibalism and infection.
Attention! Egg-carrying shrimp with visible brood chambers can be easily confused with spore-infected shrimp. But unlike healthy specimens, where brood chambers and internal organs are clearly delimited, spore-infected shrimp have organs that are affected and overgrown.
Fungal diseases, Bacterial and Viral infections in shrimp.
Last changes and additions made on September 24, 2012.
