How to keep goldfish successfully – four key tips from Pete the Vet

Movies sometimes make people want the wrong type of pets

Movies often prompt children (and adults) to want certain pets, but this often doesn’t create good outcomes.  Examples from the past include Great Dane dogs (Scooby Doo), Dalmatians (101 Dalmatians) and Huskies (Vampire movies etc).  It’s easy for people to be inspired to choose the wrong pets for the wrong reasons.

Finding Dory has made some people want “a fish like dory”

Dory is a “Blue Tang” fish also known as the “Palette Surgeonfish”. This is a marine (salt water) aquarium fish from the Pacific Ocean, so is difficult enough to keep – it’s specialised, and not suitable for children.
It makes far more sense to adapt the movie story to a more appropriate situation

A couple of goldfish in a Dory themed tank makes more sense

  • Cold water, fresh water fish are the best pet fish to start with.
  • The goldfish is the most popular fish but they often fall ill and die so many people are put off: they shouldn’t be.
  • The commonest cause of a problem is poor environment, especially poor water quality.
  • The problem is caused by poor husbandry so it’s essential to get the basics right from the start.
  • It’s best to find a good pet shop and ask them for detailed advice

four Key tips for successful fish keeping

The four main issues affecting fish tanks are

  1. Stocking level
  2. Filtration
  3. Feeding
  4. Water changes

1. Stocking level

You need to measure the surface area of water and only put in the number of fish that this allows.
In a coldwater aquarium, you should allow 60 square cm for each 1 cm of fish body length excluding the tail
For example, in a 60 x 30 cm tank you can keep a total of 30 cm of combined fish body length, such as three 10 cm-long fishes or two 15 cm-long fishes

2. Filtration

There are different types available: for long term fish keeping success, a simple electrical filter is essential, both to filter debris from the water but also to mix the water so that fresh oxygenated water is continually pushed down to the bottom of the tank to give the fish more oxygen.

3. Feeding

Overfeeding is the most common mistake in fish keeping.
The basic rule is that any food not eaten up in two or three minutes is too much.
If you have a water quality problem, stop feeding until the problem is sorted, to reduce the level of waste in the water.
Then resume feeding very lightly: once a day as a maximum
Remember that goldfish can go for up to two weeks without food – for example, when you go on holiday, it can be safer to leave fish unfed rather than to allow a neighbour to accidentally pollute the tank by overfeeding them.

4. Water changes

The simple rule of thumb is to change 25% of the tank per week every week
It’s best to use a test kit to monitor water quality but not essential. Ask in your local pet shop about this.
If you have a water quality problem, change 50% of the tank water every day until the level of nitrate falls to the correct level
Use a water conditioner to treat tap water, to remove the chlorine and any dissolved heavy metals.

For more on keeping goldfish, listen to my weekly podcast or watch the Ireland AM video clip below.

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