Rcpilot
Reef enthusiast
http://www.petsforum.com/personal/trevor-jones/marineich.html
I'll save you the trouble of reading through the whole thing, since so many of you have such short attention spans. Scroll to the bottom of the article and see the part that I put in BOLD
_________________________________________________________
Marine "Ich" or "White Spot" is probably the most frequent fish disorder encountered by aquarists keeping tropical marine fish. It is also probably the disorder that is most misunderstood by aquarists. However, because this disorder is also encountered in aquaculture, substantial research has been undertaken and the picture is somewhat clearer than many believe.
What causes marine "Ich"?
Marine "Ich" is caused by a ciliated protozoan called Cryptocaryon irritans Brown 1951. Ciliates (Phylum Ciliophora) are one of the largest groups of protozoans and all posses cilia or compound ciliary structures for food acquisition or locomotion at some point in their life cycle. Of the some 7200 species that have been described, around one third are ecto- and endo- commensals and parasites (Ruppert and Barnes, 1994). C. irritans is an obligate ectoparasite (Dickerson and Clark, 1996) which means that it is an external parasite that needs the fish host to complete its life cycle. The name 'Marine "Ich"' has been coined because it is essentially the marine equivalent on Ichthyophthirius multifiliis Fouquet, 1876, or "Ich" for short. While the two species of ciliates have superficially similar life cycles and signs, they have been found to be only distantly related (Wright and Colorni, 2002) .
The life cycle of C. irritans
The life cycle stages of C. irritans
C. irritans has a four stage life cycle, as shown in Figure 1. The parasitic stage (trophonts) is the one that results in the appearance of white spots all over the fish. The trophonts burrow under the skin where they feed on body fluids and tissue debris. When the trophonts first infect the fish they are small but grow as they feed and so the white spots are initially small but get larger as they mature. Once mature, they drop off the fish and sink/swim down to the substrate where they encyst and begin to reproduce. In this stage they are called tomonts. After a number of days in which the tomonts divide, the cyst ruptures, releasing the tomites. Tomites may differentiate into theronts, the infective stage, which actively seek a host to reinfect.
Figure 1: The life cycle of C. irritans (After Colorni, 1987).
When the theronts (parasitic stage) are embedded in the skin of the fish, the fish secrete a thick layer of mucus in response to the irritation and they are protected from outside influences. This makes treatment of infected fish difficult.
The timings of the stages of C. irritans
Table 1 shows the lengths of each of the stages of C. irritans as determined by various authors and studies. Despite each of the authors working in different locations and having different sources for the parasites, the findings are consistent. Trophonts will attach to the fish for at least 3 days (78 hours) and as long as 7 days at around 25°C. When the trophonts drop off the fish, they can take as little as 30 minutes and up to 24 hours to reach the substrate, with the majority encysting towards the shorter end of the range. The reproductive stage appears to be quite variable. Reproduction can be complete in as little as 84 hours (3 days) but can extend to as long as 12 days and even longer.
Table 1: Lengths of stages of C. irritans from various studies. Reference Trophont Free-swimming Trophont Tomont Theront Temperature Burgess and Matthews, 1994a 78 - 113 hrs 2 - 8 hrs 84 hrs - 35 days up to 18 hrs 23 - 27°C Burgess and Matthews, 1994b 78 - 113 hrs
10 - 12 days
24 - 26°C Cheung et al., 1979
30 mins - 24+ hours 8 - 9 days
25°C Cheung et al., 1979
30 mins - 24+ hours 5 - 7 days
30°C Colorni, 1985 3 - 7 days up to 18 hours 3 - 28 days 24 - 48 hours 24 - 27°C Diggles and Lester, 1996a 3 - 7 days
3 - 12 days
25°C Diggles and Lester, 1996b 4 - 6 days
3 - 15 days
25°C Yoshinaga and Dickerson, 1994 6 - 7 days
4 - ? days up to 12.5 hours 23 - 25°C
The Signs of Marine "Ich"
The first sign of Marine "Ich" infections are white spots. The fish develop small white cysts on their body surfaces (Figure 2). The eyes may also become infected causing clouding of the eyes and even blindness. Fish may also scratch, show a loss of appetite and show laboured breathing, especially when the gills are infected. Some fish may even jump out of the tank.
Figure 2 a & b: Chaetodon guentheri with severe C. irritams infection.
As the integument of the fish is often compromised, particularly with severe infections, the fish may suffer degredation or even loss of osmotic control.
Immunity
Innate Immunity
Innate immunity refers to the general response to an invading pathogen or parasite regardless of that pathogen or parasite encountered (Dickerson and Clark, 1996). This form of immunity does not rely on previous encounters and includes generalised reactions such as secretion of mucus, but may include specific host cell responses (acquired genetically).
While little formal study has been performed on innate immunity of marine fish to C. irritans, innate immunity of freshwater fish to I. multifiliis, both between and within host species suggests that the former may be possible. Collective anecdotal evidence from marine aquarists lends weight to the idea that some species, such as chaetodontids (butterflyfish) and acanthurids (surgeonfish and tangs) may be more prone to Marine "Ich" infections, whereas other species such as callionymids (dragonets) are not at all. Intraspecific differences in innate immunity would be much harder to detect through random observation.
Acquired Immunity
Acquired immunity occurs when the response is specific to the invading organism, which is recognised directly or through antigens (Dickerson and Clarke, 1996). Colorni (1987) first suggested that marine fish could acquire some immunity to C. irritans by surviving several infections. Burgess and Matthews (1995) demonstrated acquired immunity in the thick-lipped mullet, Chelon labrosus. They found that 82% of fish that had been previously exposed to high levels of theronts were immune to a secondary exposure.
Treatment
There are only two proven methods for the treatment of Marine "Ich", copper and hyposalinity. Neither method can be used in the presence of elasmobranchs (sharks and rays) or invertebrates and so treatment must be performed in a quarantine or hospital tank. Hyposalinity is the preferred treatment as it is not dangerous to the fish and actually eases osmotic stress on the fish. Hyposalinity can also be performed in the presence of calcareous substrates.
For a more detailed description of hyposalinity, please see: Hyposalinity.
Copper is toxic to both fish and invertebrates and must be used with care. As calcium carbonate absorbs copper, copper cannot be used in tanks with calcareous substrates, such as coral sand or shell grit, or with coral decorations. Copper should not be used in the presence of invertebrates or elasmobranchs. Copper is not very stable in sea water and the levels must be continuously monitored.
Other methods for the treatment of marine "Ich" have been described, but, generally, they limited success. One of the problems with assessing treatment methods for marine "Ich" is that fish may recover through acquired immunity giving the impression that the treatment was effective when perhaps the fish would have recovered on their own.
It is worth noting that many people have had apparent success with adding garlic to the food of infected fish. Garlic is well know for its therapeutic effect, particularly in humans and it is possible that the same active ingredients may be effective in fish, too. As with other treatments, it is difficult to assess the effectiveness of garlic as a dietary supplement. The theory behind the use of garlic is to aid and strengthen the fish's immune system's ability to recognise and react to the parasite.
Continued in next post:
I'll save you the trouble of reading through the whole thing, since so many of you have such short attention spans. Scroll to the bottom of the article and see the part that I put in BOLD
_________________________________________________________
Marine "Ich" or "White Spot" is probably the most frequent fish disorder encountered by aquarists keeping tropical marine fish. It is also probably the disorder that is most misunderstood by aquarists. However, because this disorder is also encountered in aquaculture, substantial research has been undertaken and the picture is somewhat clearer than many believe.
What causes marine "Ich"?
Marine "Ich" is caused by a ciliated protozoan called Cryptocaryon irritans Brown 1951. Ciliates (Phylum Ciliophora) are one of the largest groups of protozoans and all posses cilia or compound ciliary structures for food acquisition or locomotion at some point in their life cycle. Of the some 7200 species that have been described, around one third are ecto- and endo- commensals and parasites (Ruppert and Barnes, 1994). C. irritans is an obligate ectoparasite (Dickerson and Clark, 1996) which means that it is an external parasite that needs the fish host to complete its life cycle. The name 'Marine "Ich"' has been coined because it is essentially the marine equivalent on Ichthyophthirius multifiliis Fouquet, 1876, or "Ich" for short. While the two species of ciliates have superficially similar life cycles and signs, they have been found to be only distantly related (Wright and Colorni, 2002) .
The life cycle of C. irritans
The life cycle stages of C. irritans
C. irritans has a four stage life cycle, as shown in Figure 1. The parasitic stage (trophonts) is the one that results in the appearance of white spots all over the fish. The trophonts burrow under the skin where they feed on body fluids and tissue debris. When the trophonts first infect the fish they are small but grow as they feed and so the white spots are initially small but get larger as they mature. Once mature, they drop off the fish and sink/swim down to the substrate where they encyst and begin to reproduce. In this stage they are called tomonts. After a number of days in which the tomonts divide, the cyst ruptures, releasing the tomites. Tomites may differentiate into theronts, the infective stage, which actively seek a host to reinfect.
Figure 1: The life cycle of C. irritans (After Colorni, 1987).
When the theronts (parasitic stage) are embedded in the skin of the fish, the fish secrete a thick layer of mucus in response to the irritation and they are protected from outside influences. This makes treatment of infected fish difficult.
The timings of the stages of C. irritans
Table 1 shows the lengths of each of the stages of C. irritans as determined by various authors and studies. Despite each of the authors working in different locations and having different sources for the parasites, the findings are consistent. Trophonts will attach to the fish for at least 3 days (78 hours) and as long as 7 days at around 25°C. When the trophonts drop off the fish, they can take as little as 30 minutes and up to 24 hours to reach the substrate, with the majority encysting towards the shorter end of the range. The reproductive stage appears to be quite variable. Reproduction can be complete in as little as 84 hours (3 days) but can extend to as long as 12 days and even longer.
Table 1: Lengths of stages of C. irritans from various studies. Reference Trophont Free-swimming Trophont Tomont Theront Temperature Burgess and Matthews, 1994a 78 - 113 hrs 2 - 8 hrs 84 hrs - 35 days up to 18 hrs 23 - 27°C Burgess and Matthews, 1994b 78 - 113 hrs
10 - 12 days
24 - 26°C Cheung et al., 1979
30 mins - 24+ hours 8 - 9 days
25°C Cheung et al., 1979
30 mins - 24+ hours 5 - 7 days
30°C Colorni, 1985 3 - 7 days up to 18 hours 3 - 28 days 24 - 48 hours 24 - 27°C Diggles and Lester, 1996a 3 - 7 days
3 - 12 days
25°C Diggles and Lester, 1996b 4 - 6 days
3 - 15 days
25°C Yoshinaga and Dickerson, 1994 6 - 7 days
4 - ? days up to 12.5 hours 23 - 25°C
The Signs of Marine "Ich"
The first sign of Marine "Ich" infections are white spots. The fish develop small white cysts on their body surfaces (Figure 2). The eyes may also become infected causing clouding of the eyes and even blindness. Fish may also scratch, show a loss of appetite and show laboured breathing, especially when the gills are infected. Some fish may even jump out of the tank.
Figure 2 a & b: Chaetodon guentheri with severe C. irritams infection.
As the integument of the fish is often compromised, particularly with severe infections, the fish may suffer degredation or even loss of osmotic control.
Immunity
Innate Immunity
Innate immunity refers to the general response to an invading pathogen or parasite regardless of that pathogen or parasite encountered (Dickerson and Clark, 1996). This form of immunity does not rely on previous encounters and includes generalised reactions such as secretion of mucus, but may include specific host cell responses (acquired genetically).
While little formal study has been performed on innate immunity of marine fish to C. irritans, innate immunity of freshwater fish to I. multifiliis, both between and within host species suggests that the former may be possible. Collective anecdotal evidence from marine aquarists lends weight to the idea that some species, such as chaetodontids (butterflyfish) and acanthurids (surgeonfish and tangs) may be more prone to Marine "Ich" infections, whereas other species such as callionymids (dragonets) are not at all. Intraspecific differences in innate immunity would be much harder to detect through random observation.
Acquired Immunity
Acquired immunity occurs when the response is specific to the invading organism, which is recognised directly or through antigens (Dickerson and Clarke, 1996). Colorni (1987) first suggested that marine fish could acquire some immunity to C. irritans by surviving several infections. Burgess and Matthews (1995) demonstrated acquired immunity in the thick-lipped mullet, Chelon labrosus. They found that 82% of fish that had been previously exposed to high levels of theronts were immune to a secondary exposure.
Treatment
There are only two proven methods for the treatment of Marine "Ich", copper and hyposalinity. Neither method can be used in the presence of elasmobranchs (sharks and rays) or invertebrates and so treatment must be performed in a quarantine or hospital tank. Hyposalinity is the preferred treatment as it is not dangerous to the fish and actually eases osmotic stress on the fish. Hyposalinity can also be performed in the presence of calcareous substrates.
For a more detailed description of hyposalinity, please see: Hyposalinity.
Copper is toxic to both fish and invertebrates and must be used with care. As calcium carbonate absorbs copper, copper cannot be used in tanks with calcareous substrates, such as coral sand or shell grit, or with coral decorations. Copper should not be used in the presence of invertebrates or elasmobranchs. Copper is not very stable in sea water and the levels must be continuously monitored.
Other methods for the treatment of marine "Ich" have been described, but, generally, they limited success. One of the problems with assessing treatment methods for marine "Ich" is that fish may recover through acquired immunity giving the impression that the treatment was effective when perhaps the fish would have recovered on their own.
It is worth noting that many people have had apparent success with adding garlic to the food of infected fish. Garlic is well know for its therapeutic effect, particularly in humans and it is possible that the same active ingredients may be effective in fish, too. As with other treatments, it is difficult to assess the effectiveness of garlic as a dietary supplement. The theory behind the use of garlic is to aid and strengthen the fish's immune system's ability to recognise and react to the parasite.
Continued in next post:
