How to Zfish: A guide for Mystics

Welcome new Mystics!  We hope you are as excited as we are about this brand new mode of play!  Our new data set, Zfish, will be played differently than Eyewire cells, so here are some instructions and helpful tips to get you started.

General gameplay flows as follows:

Player A claims a cell  –> Player A completes/releases cell to Player B –> Player B claims cell –> Player B completes/releases cell to Need Admin–> Admin checks cell and when thoroughly complete, removes from cell list. See this list for the latest completions.

Zfish Basics

  • In Mystic, each player owns his or her own cell. You begin by claiming a cell, turning on MSTY (your partner in Zfish, an advanced AI player), then watching the cell grow before your eyes!
  • Intervene when there are mergers or if the cell gets stuck. The cells are largely grown by MSTY, but she is not as good as a Scythe and needs your help to extend branches past difficult traces. She also doesn’t know when she creates mergers.
  • Mystic does not use simple consensus, as in Eyewire play. It has properties of reap-growing and you can adjust the segmentation higher or lower on an individual cube basis.
  • It is your job as a Mystic class player to help MSTY grow the cell when she gets stuck. But remember, MSTY is the primary player here, and your job is most similar to Scything — that is, fixing MSTY’s mistakes and then continuing to let her grow the cell from there.
  • With that in mind, all Mystic activities should be confined to reaping and Scythe Completing. You will earn double Scythe point for any cubes you reap, but Zfish cubes are so big that volume-based Eyewire points would cause huge score inflation. So please do not trace these cubes or reapgrow them at all, unless MSTY is stuck.
  • Advanced Mystic gameplay is described in detail here.

How to Play

Notice a shiny new addition to your Scouts Log: a Mystic Section!

eyewire, scouts log, scoutslog, mystic, msty, change cell, eyewire UI, UI demo, scythe



  1. Claim your cell!
    1. Available cells are listed in Need Player A.
    2. Jump to your cell. Use the Start Playing menu to Claim the cell.
      1. You may only claim one cell at a time.
  2. Turn on MSTY. The yellow MSTY label shown as OFF at the top of the page will turn to a blue ON.
    1. Never leave Eyewire while MSTY is on – she can easily and quickly spawn huge mergers that slow down the entire system.
  3. MSTY will immediately begin growing the cell.
    1. You can tell that MSTY has played a cube when the cube reaches weight 3. If the end of a branch has reached weight 3, you should check it to see if there is a continuation needed. If you see a small turquoise cube appear above the branch that means it will soon spawn new cell growth and you should wait until it’s finished before checking.
  4. Inevitably MSTY will make a merger (keep a close eye near somas) or get stuck on a thin branch. Here’s where your superhuman powers come in handy.
    1. Reap the cube using the new MSTY threshold slider. eyewire, scouts log, scoutslog, mystic, msty, change cell, eyewire UI, UI demo, scythe
      1. Decreasing the threshold joins more segments; increasing the threshold separates the segments. This allows you to have fine control over the segments you add and mergers you delete. MSTY grows the cells at a 0.3 threshold.
    2. If you see a merger, immediately turn off MSTY while you correct it.
      1. Remember to turn MSTY back on when you’ve cleared the merger.
    3. Scythe complete branches as you go along. This will help you remember what you’ve already checked, and indicates to the next player that the cell is completely checked.
  5. When you and MSTY have mapped the cell all the way to completion and checked all the branches, mark it as Done/Need Player B.
    1. If for any reason you are unable to finish your cell in one week, you may Release the cell.


  1. Open the Need Player B section of the Mystic Scouts Log to see which cells are available for Player B.
  2. Jump to the cell and claim it. You will see a cell that has been fully grown.
  3. Turn on MSTY.
  4. Scythe complete the cell.
    1. Do a thorough check over the cell to make sure that Player A did not miss anything. If you find missing branches or uncaught mergers, reap them.
  5. Once the cell is complete, set the cell to Need Admin using the Start Playing menu. This indicates to an Admin that Player B has finished and the cell is ready for a final check from Grim Reaper.

Using MSTY thresholding

  •  Thresholding is currently unique to Zfish cells. Thresholding will join or split apart segments according to MSTY’s confidence that they go together.
  • You can use the MSTY threshold bar to adjust the confidence MSTY needs to have to join segments together. 0 indicates 0% confidence needed, and 1 indicates 100% confidence needed. For example, if the threshold is set to .45, MSTY will join together any segments when she has 45% or more confidence that they go together. If the threshold is set to .75, she needs to be 75% sure two pieces go together before she will join them.
  • MSTY in-cube and overview thresholding are different. Thresholding used for the overview is consistent, where as in-cube thresholding can be altered. Basically in-cube thresholding is an efficiency tool for the player, but does not affect MSTY’s initial trace.
  • Thresholding may need to be adjusted from cube to cube. If you have a branch with very clear boundaries in the 2D, you can probably get away with setting the threshold closer to 0. If there are barely any visible boundaries, it’s better to get closer to 1 for the most precise trace.

Important tips (please read, they’re really important!)

  • Downsampling is your friend. Downsampling will get rid of the “staircasing” effect you see in the 3D model, and will also help cubes load more efficiently. To use downsampling, go to the settings menu and click on “3D detail.” Set to medium or low for image smoothing and faster loading.

eyewire, scouts log, scoutslog, mystic, msty, change cell, eyewire UI, UI demo, scythe, mystic, downsampling

  • ALWAYS check to make sure a branch has reached weight 3 before trying to fix it. If it is at weight 0, don’t reap it.
  • Once you release a cell, you should not be making corrections.  If you’ve sent your cell off to be checked by Player B, or an Admin, it no longer belongs to you.  If your name is not currently active on the cell you should not be changing anything.  You are certainly free to check over any branches, but please do not make any alterations.
  • Z-fish cubes only have one usable plane (Z plane). The other planes may have very limited use at times, but generally are too pixelated to be helpful. You’ll have to get used to this slightly different method of play.
  • The 1 plane that MSTY does have has 2D images that are much clearer than Eyewire images. These images show organelles as well as cell boundaries, so you will have to get used to spotting the difference between a continuing branch and an organelle. Slices are also farther apart than they are in the Eyewire data set, so watch out for big jumps between slices, and scroll back and forth to make sure you’ve found a good continuation.
  • Don’t be afraid to experiment with thresholding. If your threshold is too low and too many segments are joined, you can always make it higher, and those segments will split apart again. I tend to stay in the .4 – 1 range, but you can use what works for you.
  • Starting out, all players can assume the position of either Player A or Player B. Please try both roles so that you get accommodated to doing both kinds of play. I suggest switching every cell between being Player A and Player B. If you find one column is getting much longer than the other, please switch to the short column and fill that role until things even out.
  • We have been asked to do MSTY cells thoroughly and completely. This means that, unlike with Eyewire, you SHOULD add every piece of dust, even if it is in an internal part of the cell. This means you need to add dust to the inside of CBs as well. Every CB cube should be checked for nubs and additional branches.
  • Thoroughly and completely means that we also need to complete the entire cell with no missing pieces. If branches cut off because they hit the edge of the data set, that it okay. If there is a problem, such as a branch that has ceased to grow despite attempted correction, or unclickable segments, the cell will need to be fixed. If this is the case you may continue to complete the cell as normal, but please attach a note to the problem cube with the details of the problem and set to “need admin.”
  • There are some frequent problems that actually do have solutions. The most common one is a branch not extending despite reaching the edge of the cube. Often this problem occurs because MSTY has grown the branch through one cube, but missed it in an overlapping cube. Try to find the cube where she missed it and add it back in. Using the “highlight” function is very useful in situations like these. If you can’t find the extension in an adjacent cube, try using show parent/show children to see if you can find it, because in some cases it may not be seeded.
  • Zfish uses a different color for each segment, rather than the uniform turquoise that Eyewire uses. I find this very useful! Others may find it takes some time to get used to. These colors also don’t show the consensus agreement when reaping like the Eyewire cubes do.
  • An Admin will always do a final check on a cell before it is declared complete. However, ideally an Admin will find little to nothing to add. For the sake of efficiency, we hope to eventually be able to complete Zfish cells with 2x coverage rather than 3x coverage. But to be able to work towards this goal, we need to prove that 2x coverage is sufficient.

If you have any other questions about Zfish, just check in with an Admin! Admins from both Boston and Princeton are knowledgeable about Zfish and should be able to help.

Happy Zfishing!