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How to use the Ecology & Fish data explorer app

The data explorer can be used to search for and filter the Environment Agency's freshwater fish and ecology survey open data. This data is taken from the National Fish Populations (NFPD) database and Biosys (Biological survey database). By using the data explorer's filters you can focus on the areas that you are interested in, and then download the data particular to your needs.

If you are interested in all the data available, you can download all of the raw data on the downloads page. You cannot download the full dataset using the map interface as the datasets are too large.

To keep load times to a minimum, try and restrict the data to particular years or areas. The rest of this page will show you how to use the explorer interface to do that. There is also a troubleshooting and tips section at the bottom of this page if you are having problems loading the explorer.

1. Pre-load selectors


Four datasets are displayed: fish, invertebrates, macrophytes and diatoms. You can pre-select the data you are interested in to display on the map, using the tick boxes.

Dataset selector

Adjust the slider to only load data for the years you are interested in.

Years slider selector
Base map

You can also choose from different base maps to help you draw your search area on the map. Please note that these datasets are England-only so although you can move the map to other countries you will not see any data displayed.

Base map selector

The default map is the OpenStreetMap, which is suited for use on a larger map when you are zoomed out. In order to see details such as the river outline more easily, when zoomed in, try switching to the OpenTopoMap. For satellite images try the Esri.WorldImagery map.

2. Draw an area

Use the tools on the left of the map to draw an area on the map and display the ecology and/or fish sites. You can use either the rectangle tool, or the polygon tool if you require a more complex shape. You must join the last section of the polygon to your polygon starting point in order to complete the shape (or click on the ‘Finish’ button). Data is only returned for a completed shape.

You can zoom in and out of the map using the ‘+’ or ‘-‘ buttons. You can also zoom to a river or geographical area, for example a town or post-code that you are familiar with, by using the search button. For example searching on ‘River Severn’ will bring up several options, you can then select the most appropriate and the map will zoom in to that area and highlight the search area with a blue circle. You will then need to draw around the area you are interested in using the rectangle or polygon tool to display the data points.

Map: draw an area Map: display markers in area

Once a shape is drawn, you can click on the edit tool to adjust its shape.

Edit a shape on the map

Whenever you finish drawing or editing an area, the explorer will display any points on the map for which there are data. You cannot delete a shape so, to search on a completely different area, simply draw a new shape and the new data will be displayed (the old shape will disappear).
Please note, that if you have drawn a large area, or chosen a large timeframe, then the points on the map may take a while to load. You may need to reduce your search area or timeframe and try again.

You can click on a point on the map to see a pop-up box with basic information about the site and dataset.

Map pop-up

The information displayed in this example is for the invertebrate dataset. Please note that where sites have more than one dataset associated this additional information will not be visible on the map (however it will still appear in the data tables). For example, this particular site also has diatom data associated but to view the orange diatom marker on the map you would need to un-tick the overlying invertebrate dataset.

3. View and refine the data

The full data is shown beneath the map in different tabs for each dataset.

Data tabs

You may choose to further refine your data before downloading. Use the filters above the data table to reduce the data further e.g. by Species name. Data will be filtered across all relevant tabs for each dataset that the filters apply to. So, for example, if you filter on Species name when viewing the Fish counts tab, all the other tabs within the fish dataset will be filtered. The filtering will not apply to invertebrates, diatoms or macrophytes. Filters only apply to the dataset you are viewing when you apply them.

If you are using filters, you will need to use a key word or partial word that matches the data. For example: if searching for Brown trout you need to search on either the word “Brown” or a partial match such as “Brow”. To enable the filter press ‘Filter’ and to remove the filter press ‘Clear’. Note that the filters are not case-sensitive.

Filtered data table

When using the date filters a calendar will pop up. Use the arrows to scroll through the months or click into the Year text e.g. January 2020 to see the option of selecting a different year.

Select new dates with the calendar pop up

You can also use the "Quicksearch" box at the top right of each data table, this will search across all records in the data table and show you any resulting matches. The Quicksearch feature will not affect the resulting download, but is a handy way to check your data contains something you are interested in. You can use partial words/phrases in the Quicksearch box and it is not case-sensitive.

The quicksearch functional

Please note that the datasets are displayed with some columns hidden as default to make it easier to scan through the main data fields. All columns, whether hidden (or not), will be brought through into any data downloads. If you wish to customise the columns you can see in the interface, you can select and de-select them using the column visibility button.

Column visibility

4. Download data

Once you have refined your data to your satisfaction, you can use the Download button to download a zip file to your computer. The zip file will contain several csv files for each of the datasets.

Download button


You can access the documentation for each of the individual datasets on the documentation page. The documents contain explanations of the fields and also include data caveats and warnings to ensure you understand and get the best possible use out of these datasets. Please read through them before using the data.

Tips and Troubleshooting

If you have problems loading the map there are certain things you can try:

  • Use Google Chrome (or Firefox) as your internet browser instead of Internet Explorer.
  • Press F5 or the ‘reload this page’ button reload button
  • Try clearing your cache. Instructions on how to do this when in Google Chrome are here.

When looking at an area of interest for the first time on the map, it can be useful to draw a slightly larger area to understand the spread of sites. You can then zoom in further and draw a more targeted area around the data points you are interested in. This will reduce the amount of data in the download and subsequent filtering or manipulation of the data.