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Bacterial Infection

Introduction

Bacterial infections come in many different forms. Bacterial infections may be red streaks and sores like is shown in the Purple Stripe Dottyback (Picture 1), dark patches like the Spotted Yellow Eye Kole Tang (Picture 2) and the One Spot Foxface (Picture 3), light patches, torn fins which are known as fin rot. Bacterial infections can also be cloudy eyes, and tattered fins that are in poor condition shown above in the Forktail Blenny (Pictures 4 & 5).

Types of Bacterial Infection

There are two different types of bacterial infections, Gram-positive and Gram- negative. The difference between these two bacteria is in the material that makes the cell wall, called Peptidoglycan. The peptidoglycan in Gram-negative is a thin cell wall and has an outer membrane layer, and Gram-positive bacteria has multiple layers of peptidoglycan thicker than the Gram-negative and no outer layer membrane. Gram- positive bacterial infections are the slower acting of the two types, but can be difficult to spot before it’s too far gone. Gram negative bacterial infections are caused by gram negative organisms. This is fast acting, and can kill a fish within the first 24 hours of spotting it. There are many reasons for the Gram negative bacteria to arise, and the top reason is from stress. The Dottyback (Picture 1) we ordered via overnight shipping and the fish spent upwards of 12 hours on a plane and arrived stressed. With the fish being stressed, their immune system is more susceptible to disease and bacteria because of their weakened condition.

Treatment Options

Some of the treatment options we use for bacterial infections are Kanaplex, Furan 2, Metroplex, and Tetracycline. These medications can be combined together and not harm the fish. By combining a Gram-positive and Gram-negative medication creates a broad spectrum antibiotic.

Purple Stripe Dottyback

The Purple Stripe Dottyback (Picture 1) came in for the wholesaler and within a few days it had developed a bacterial infection circled in red near its caudal fin. This infection rapidly spread. While moving the Dottyback (Picture 1), it succumbed to the bacterial infection. This bacterial infection was most likely a Gram-negative infection, and killed the fish within the first 24 hours of it being spotted. Due to the size and stature of the Purple Stripe Dottyback (Picture 1), and the stress of transit weakened its immune system, this fish was more likely to succumb to injury.

Spotted Yellow Eye Tang and One Spot Foxface

This Spotted Yellow Eye Tang (Picture 2) and the One Spot Foxface (Picture 3) were in the same tank together with a Bicolor Angel that developed flukes, and were all getting treated with Chloroquine Phosphate and Methylene Blue for Ich due to an Ich outbreak from a new shipment of fish. These two fish developed a different disease compared to the Bicolor Angelfish. These two saltwater fish developed a bacterial infection which is shown in the dark patches in the Tang's (Picture 2) face and on the body and cloudy eyes of the Foxface (Picture 3) that is circled in red. The treatment option we’re currently using on these two fish is Tetracycline. Again, stress allows a marine fish to be more susceptible than normal bacteria and parasites partly due to a reduced slime coatl. The One Spot Foxface’s (Picture 3) bacterial infection was too extreme and it did not survive. This could be because it was in the Chloroquine Phosphate and Methylene Blue. As a result a Gram-negative bacterial infection occurred, which could not be treated quickly enough to save it. Thankfully, the Spotted Yellow Eye Tang’s (Picture 2) facial bacterial infection was spotted and treated before it spread to the rest of its body, and it is now healed in a 20 gallon tank with regular salt water with no medication to see how it reacts to unmedicated water. If the Tang (Picture 2) continues to do well, it will be moved with the regular, healthy fish, and will be placed online for sale.

Forktail Blenny

The Forktail Blenny (Pictures 4 & 5) was also a new fish along with the Dottyback (Picture 1), and it was not eating, and the fish was hanging vertically on the side of the tank. The Forktail (Pictures 4 & 5) was removed and put into quarantine for the rotting of the fins, and the eye was also cloudy, which are both symptoms of a bacterial infection. The Blenny (Pictures 4 & 5) did not survive the first week of being brought in from the new shipment. The infection on the Blenny (Pictures 4 & 5) could also have been too far developed to stay alive to get through treatment like the Dottyback (Picture 1), and there was also a Canary Blenny in the tank.

Conclusion

Bacterial infections can be shown as red streak sores, dark patches, light patches, and torn and tattered fins. These infections can affect different types of fish, such as a small fish like the Purple Stripe Dottyback (Picture 1), a larger fish like the Forktail Blenny (Pictures 4 & 5), and even larger fish such as the One Spot Foxface (Picture 3), and the Spotted Yellow Eye Kole Tang (Picture 2). As we have found, the larger the fish is with a bacterial infection, the more likely it is to survive treatment. Bacterial infections can spread fast in a fish, and can cause death within the first 24 hours of contraction. There are many reasons for Gram-negative and Gram-positive bacteria to arise, and the top reason is from stress. It is important to keep a tank clean with water changes, to not overfill the tank with fish, and make sure to observe fish in a tank before the spread of disease affects all the fish in a tank. By: Sarah Cooley

References

Sources: Silhavy, Thomas J, et al. “The Bacterial Cell Envelope.” Cold Spring Harbor Perspectives in Biology, Cold Spring Harbor Laboratory Press, retrieved [July 18, 2022] available online at >https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2857177/#:~:text=Gram%2Dnegative%20bacteria%20are%20surrounded,found%20in%20the%20Gram%2Dnegatives Pet Fish Doctor. (2022). Bacterial Disease, retrieved [July 11, 2022] available online at http://www.petfishdoctor.com/bacterial-diseases.pml#:~:text=Most%20bacterial%20infections%20are%20caused,Vibrio%20usually%20effects%20marine%20fish User melypr1985. “Fish Disease Index - Pictorial Guide.” REEF2REEF Saltwater and Reef Aquarium Forum</span >, retrieved [July 11, 2022] available online at https://www.reef2reef.com/ams/fish-disease-index-pictorial-guide.199/ Yanong, Roy. “USE OF ANTIBIOTICS IN ORNAMENTAL FISH AQUACULTURE.” CIR 84/FA084: Use of Antibiotics in Ornamental Fish Aquaculture, retrieved [July 18, 2022] available online at>https://edis.ifas.ufl.edu/publication/FA084<