Disclaimer: Try at your own risk. Treatment of this sort is inherently dangerous to both you and your tank. As noted above, this is a last resort option. Wear PPD when handling any antibiotics.
I have a 40 breeder SPS tank that I started with Florida live rock in 2021. At first it did well, but over the past 6-12 months I started seeing widespread STN-type symptoms in otherwise healthy corals and slow growth. Corals would lose colors, brown out (particularly at the tips), then start receding from the base and tips. ICP did not demonstrate anything unusual and nutrients were in the range I like (nitrate ~5-10, phosphate 0.10-0.15). I began to suspect SCTLD (Stony Coral Tissue Loss Disease) brought in on the live rock. I ran across this post:
www.reef2reef.com
which demonstrated very similar appearing symptoms which improved with ciprofloxacin treatment. I decided to try the methods they used and treated the tank empirically with ciprofloxacin (one 400 mg tablet crushed in RODI and added daily for three days). (Unfortunately, I did not think to do an Aquabiomics test prior to this.) On day 4, I started passive carbon filtration. The only issue related to this treatment was a forktail blenny that developed swim bladder issues after treatment and eventually succumbed. Everything else was fine. Within about a month, approximately 50% of my corals were showing mild improvement, although the remainder continued to show STN/SCTLD-type symptoms with ongoing tissue recession and subsequent death.
Treatment of SCTLD in wild corals is through the use of a paste form of amoxicillin (I suspect the original form was amoxicillin mixed with zinc-free denture cream, but that is only a guess) applied at the margin of SCTLD:
www.frontiersin.org
This has been very effective at stopping progression of the disease but doesn't prevent reinfection. Probiotic treatment of SCTLD is being developed and is effective, but isn't available yet. In addition, SCTLD has been shown to be present in sediment not just on corals, so for aquarists like myself, total tank treatment was clearly indicated.
Given that and the continued loss of corals in the tank, I purchased "pet grade" amoxicillin and decided to follow the dosing recommendations of 500 mg per 20 gallons of tank water (for lack of a better starting point). With a system volume of roughly 40 gallons, this would equate to two 500 mg capsules per day. My initial plan was to treat for 5 days and then start activated carbon, similar to how I treated with ciprofloxacin. Dosing entailed opening the capsules (unscrew/separate the capsule halves gently) and dumping their contents into 200 ml of RODI to make a milky solution that got dumped into the tank all at once. Please note that I wore an N95/gloves while handling the amoxicillin and would recommend the same to anyone attempting this. By day 5, the tank was looking very unhappy with loss of colors in all SPS, so only 4 days of treatment were administered and I started passive carbon filtration on day 5. By day 7, things were not improving and I lost an ORA subulata frag to RTN. I suspected that amoxicillin has a longer half life in aquaria than ciprofloxacin, so I resorted to a 95% water change (much to the displeasure of my fish). I left the passive carbon filtration going and crossed my fingers. Several corals browned out, two exquisita started losing small amounts of tissue, and one valida partially RTNed. The two exquisita got moved to my main tank (which is SCTLD/STN free) but I left the poor valida in the 40 breeder tank to see what would happen. In addition, I moved a few small pieces of live rock from my big tank into the 40 breeder to hopefully reseed the microbiome.
Two weeks later and things have vastly improved. The RTNed valida is regrowing tissue at a rapid rate and is colored up again. Several corals that languished for more than a year are suddenly branching. Colors are appearing that I had not seen before. Tissue recession appears to have stopped for all affected corals, although the most severely affected remain browned-out. Overall, a shocking response to a near lethal treatment.
In terms of recommending this as a treatment, I would have reservations.
1) Essentially, I caused a "microbiome reset" to everything susceptible to amoxicillin, good and bad. If not for having a healthy microbiome from another tank in the form of live rock and the ability to do a near-total water change, this might have led to cataclysmic loss of the tank. I would highly recommend active carbon filtration rather than passive as amoxicillin does not seem to clear as quickly as ciprofloxacin.
2) In my case, having started with Florida live rock, I assumed that the likelihood of SCTLD was high. If you didn't start with Florida live rock, I would definitely send an Aquabiomics test to verify that you have pathologic SCTLD bacteria prior to attempting this treatment.
3) I have no idea whether my dosing strength (500 mg amoxicillin/20 gallons of water) was appropriate for treatment of SCTLD or not. This will require additional attempts at treatment at varying doses and long term results to determine.
I have a 40 breeder SPS tank that I started with Florida live rock in 2021. At first it did well, but over the past 6-12 months I started seeing widespread STN-type symptoms in otherwise healthy corals and slow growth. Corals would lose colors, brown out (particularly at the tips), then start receding from the base and tips. ICP did not demonstrate anything unusual and nutrients were in the range I like (nitrate ~5-10, phosphate 0.10-0.15). I began to suspect SCTLD (Stony Coral Tissue Loss Disease) brought in on the live rock. I ran across this post:
Acro problems
So I've been dealing with some sort of issue with my corals, particularly acropora, over the course of the last 4-5 months. It's been a steady degrade, both visually and in element consumption. Before whatever happened, things were really looking good all around. My tank is a WaterBox 7225...
www.reef2reef.com
which demonstrated very similar appearing symptoms which improved with ciprofloxacin treatment. I decided to try the methods they used and treated the tank empirically with ciprofloxacin (one 400 mg tablet crushed in RODI and added daily for three days). (Unfortunately, I did not think to do an Aquabiomics test prior to this.) On day 4, I started passive carbon filtration. The only issue related to this treatment was a forktail blenny that developed swim bladder issues after treatment and eventually succumbed. Everything else was fine. Within about a month, approximately 50% of my corals were showing mild improvement, although the remainder continued to show STN/SCTLD-type symptoms with ongoing tissue recession and subsequent death.
Treatment of SCTLD in wild corals is through the use of a paste form of amoxicillin (I suspect the original form was amoxicillin mixed with zinc-free denture cream, but that is only a guess) applied at the margin of SCTLD:
Short- and Long-Term Effectiveness of Coral Disease Treatments
Since 2014, stony coral tissue loss disease (SCTLD) has led to large-scale mortality of over 20 coral species throughout the Florida Reef Tract. In 2019, in-water disease intervention strategies were implemented to treat affected corals. Two treatment strategies were employed: (1) topical...
This has been very effective at stopping progression of the disease but doesn't prevent reinfection. Probiotic treatment of SCTLD is being developed and is effective, but isn't available yet. In addition, SCTLD has been shown to be present in sediment not just on corals, so for aquarists like myself, total tank treatment was clearly indicated.
Given that and the continued loss of corals in the tank, I purchased "pet grade" amoxicillin and decided to follow the dosing recommendations of 500 mg per 20 gallons of tank water (for lack of a better starting point). With a system volume of roughly 40 gallons, this would equate to two 500 mg capsules per day. My initial plan was to treat for 5 days and then start activated carbon, similar to how I treated with ciprofloxacin. Dosing entailed opening the capsules (unscrew/separate the capsule halves gently) and dumping their contents into 200 ml of RODI to make a milky solution that got dumped into the tank all at once. Please note that I wore an N95/gloves while handling the amoxicillin and would recommend the same to anyone attempting this. By day 5, the tank was looking very unhappy with loss of colors in all SPS, so only 4 days of treatment were administered and I started passive carbon filtration on day 5. By day 7, things were not improving and I lost an ORA subulata frag to RTN. I suspected that amoxicillin has a longer half life in aquaria than ciprofloxacin, so I resorted to a 95% water change (much to the displeasure of my fish). I left the passive carbon filtration going and crossed my fingers. Several corals browned out, two exquisita started losing small amounts of tissue, and one valida partially RTNed. The two exquisita got moved to my main tank (which is SCTLD/STN free) but I left the poor valida in the 40 breeder tank to see what would happen. In addition, I moved a few small pieces of live rock from my big tank into the 40 breeder to hopefully reseed the microbiome.
Two weeks later and things have vastly improved. The RTNed valida is regrowing tissue at a rapid rate and is colored up again. Several corals that languished for more than a year are suddenly branching. Colors are appearing that I had not seen before. Tissue recession appears to have stopped for all affected corals, although the most severely affected remain browned-out. Overall, a shocking response to a near lethal treatment.
In terms of recommending this as a treatment, I would have reservations.
1) Essentially, I caused a "microbiome reset" to everything susceptible to amoxicillin, good and bad. If not for having a healthy microbiome from another tank in the form of live rock and the ability to do a near-total water change, this might have led to cataclysmic loss of the tank. I would highly recommend active carbon filtration rather than passive as amoxicillin does not seem to clear as quickly as ciprofloxacin.
2) In my case, having started with Florida live rock, I assumed that the likelihood of SCTLD was high. If you didn't start with Florida live rock, I would definitely send an Aquabiomics test to verify that you have pathologic SCTLD bacteria prior to attempting this treatment.
3) I have no idea whether my dosing strength (500 mg amoxicillin/20 gallons of water) was appropriate for treatment of SCTLD or not. This will require additional attempts at treatment at varying doses and long term results to determine.
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