How to know when your fish needs a professional vet


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It’s okay to admit you’re out of your depth. We ask a fish vet for advice on when to call in the professionals…

Being a fish vet is a great conversation starter. I’m always surprised by the number of people who aren’t aware that we exist, and take great pleasure in seeing the faces people pull when I explain what I do day to day.  

This highlights how little well known aquatic vet services are in the UK. I understand why, in so many cases, I see fish at the late stages of disease, as owners aren’t aware of the options available to them. 

Starting at home

It’s useful to begin by understanding which diseases could potentially be treated at home. Disease can largely be categorised into one of several causes: genetic; nutritional; infectious (viral, bacterial, protozoal); neoplastic (cancerous); inflammatory; and auto-immune. 

Of those likely to be treated at home, only infectious and nutritional diseases can really be addressed without advanced diagnostics (such as imaging or surgery) available through veterinary services.  

Thankfully, with an abundance of ‘over the counter’ medications and advice forums available at a click of a button, fishkeeping is largely self-reliant, seldom requiring a vet. 

My first piece of advice for at home treatment is to try and identify, as precisely as you can, what sort of disease process you have brewing. If it is an infectious disease, it’s important to further identify whether the problem is bacterial, fungal, protozoal or parasitic as each of these agents will require different drugs as part of the treatment plan. 

The following scenarios are examples of diseases that you can usually treat effectively at home, without veterinary input.

● Typical looking infectious diseases such as Whitespot disease or Saprolegnia water mould infections

● Bacterial infections not leading to high mortalities or aggressive ulcers (Fin rot, for example)

● Parasitic infections such as skin fluke/gill fluke

● Disease secondary to water quality abnormalities

Home medicating In the vast majority of cases, poor water quality or stressful events underpin the appearance of fish disease. 

Full assessment of water quality using dipstick, liquid or tablet test kits is essential before diving in with medications. Analysis of water quality could not only highlight possible causes but could help ensure the safe and effective use of some medications if later opted for. 

Certain medications can be toxic or ineffective if used in the wrong aquatic environments. For example, malachite green is more toxic in acidic and higher temperatures of water, requiring lower doses to be used to treat. Once the diagnosis has been narrowed down, the next step is to select an appropriate medication. 

Be wary of products that promise a ‘cure all’ tonic, solving five different diseases at once. Not only are you likely throwing unnecessary medications at your fish but large combinations of drugs tend to reduce the efficacy.

Targeted treatments that focus on one disease or a specific set of clinical symptoms are usually more appropriately dosed and of higher quality to the ‘all in one’ medications. 

A useful thing to do, is to look for the active ingredients given on the back of the packaging. Here is a brief (and incomplete) list of suggestions of active ingredients to look for, best suited for treating the following groups of infectious disease:

● Protozoa – Formalin and Malachite green combinations

● Fungal/water mould infections – Malachite green, Methylene blue, Indian Bay Leaf based products (PIMAFIX)

● Superficial/mild bacterial infections – Melaleuca based products (MELAFIX), Acriflavin

● Flukes – Praziquantel or Formalin-based products

Following purchase of a product, administer the medication in isolation to other medications to reduce the risk of negative interactions between the active ingredients. 

Observe the response in the fish over the next 72 hours. If after 72 hours, there has been no response, reassess the clinical situation. 

Either the diagnosis was incorrect or the problem is more complicated than first thought. Do not be tempted to double up on a dose without it being clearly stated as safe to do so on the packaging or without the guidance of a trained professional. 

When working with sick fish, less really is more in my experience. It’s often all too easy to throw everything at a clinical problem within a short space of time, but refrain from doing so as the stress alone can kill a fish.

If you do switch between medications, make sure you perform a significant water change or allow a wash out period between medications. The addition of carbon or Poly filters after treatment to remove residual medication is also a good idea. (Ed’s note: the Poly-Filter distributed by Arcadia is especially good in this role.)

Tumours can be removed by a vet.

Calling a vet

In an ideal situation, vets should be notified as early as possible if you would like help with a clinical case. As a very rough guide, I would recommend calling a vet out promptly for the following scenarios:

● Multiple deaths of fish that you can’t explain

● A fish with a mass you think should be removed surgically

●  Fish with severe or advanced signs of disease or distress. For example, a fish presenting with dropsy. 

● You have attempted at home treatment to no success. 

Of all the scenarios in which I would expect clients to call vets in for, surgical and invasive procedures are by far the most obvious. Some of the common surgical procedures performed in aquatic animal practice include mass removals (both externally and internally), enucleations (removal of an eye) and removal of excess gas from the swim bladder. 

The Veterinary Surgeons Act 1966, gives guidance on the restrictions in place to ensure that animals are only treated by those qualified to do so.

It goes without saying, that there are many important variables involved when performing surgical acts to include, anaesthetics (understanding depth and maintenance), analgesia (pain relief), anatomy and controlling unexpected events such as bleeding or post-operative infections. All of which highlight the importance of a trained and qualified clinician for such tasks. 

Ulcers may be treated at home.

Handling antibiotics

During the summer months, I frequently work with koi and goldfish suffering from bacterial ulcerative disease. A common request
from owners preceding these consultations is the request for some kind of antibiotics. 

Only following clinical assessment of a fish under a vet’s care, can antibiotics be prescribed. I am continually amazed by how many clients will have already tried a number of antibiotics before my consultation. (Ed’s note: online marketplaces have given this problem a second wind recently.)

This indiscriminate usage of antibiotics not only complicates treatment plans and compromises fish health, but is illegal in the UK. Antibiotics are listed as Veterinary Medicinal Products (VMP’s) and are only legally available through a prescription from a veterinarian. 

There are a number of important reasons for this classification but most pertinently, it’s to provide a method of control for antibiotic use, to reduce the risk of inducing antibiotic resistance, which is huge challenge facing modern medicine. 

When thinking about the reasons why someone may not choose to contact a vet for a fish health concern, there are several considerations that spring to mind. The first and obvious reason being the cost of veterinary care. Depending on the species of fish kept at home, you may be less willing to spend money on a veterinary bill. 

So far during my career I have worked on fish purchased for less than £2 up to fish valued in close to £20,000. The price spectrum is huge, as are the sentimental values placed on each fish, which makes each decision to call in a vet a particularly personal one. 

The sentience of fish is a controversial subject so I won’t explore this too much now. There is a common conception (or misconception, to my mind) that fish are somewhat replaceable, should they fall sick. I would like to encourage readers that no matter the cost of a fish, if you are suspicious of ill-health, you have the responsibility to do something about it. Whether that’s through over the counter medication or veterinary input, leaving a fish to suffer is simply not acceptable. 

Search engines gone astray

Lastly, when seeking further guidance and information on disease, be aware that not all online resources are reputable. All too frequently, Dr Google connects you with a forum where the overriding consensus is that you should immediately disinfect and depopulate your tank or pond and start again — this is potentially unnecessary heart break. 

Be aware that every clinical case is different and that there are a great number of variables involved to include water quality, number of fish affected, clinical history, type of disease present and more. What has worked for one individual on one webpage might not exactly match your clinical conundrum. 

Reach out to local aquatic stores or dealers for at home medications and advice and if you’d like to seek out veterinary expertise, The Fish Vet Society has a webpage dedicated to helping members of public find fish veterinarians local to them. Be mindful that the sooner a decision or plan of action is taken, the greater the chances of a successful recovery.