My Strategy Base for Beating Challenge Mode Tank 4 in Insaniquarium

''Note: I have beaten Challenge Mode on Tank 4 once before. How I did it I do not know. I'm making this strategy guide because I keep failing at future attempts (because you have to complete Challenge Mode eight times on each tank) over and over so much that it's really annoying me.''

Pets
I have the four-pet limit at this point, FYI.


 * Gumbo (because he really helps in protecting your fish)
 * Meryl (because she's really good for money gathering)
 * Presto (I can have him as Shrapnel and Meryl for good money, Clyde and Nimbus to help in collecting money, Rufus, Gash and Stanley to fend off aliens, Blip to work out what kinds of aliens are coming and Angie to revive dead fish)
 * My fourth choice is tricky, but I could go with...
 * Clyde (money grabbing)
 * Nimbus (keeping the money alive)
 * Rufus (fending off the aliens)
 * Stanley (can destroy alien projectiles)
 * Seymour (slower money falling)

Overall Tactic

 * 1) Start by having Presto as Shrapnel. Get the Breeder to medium size as quickly as I can.
 * 2) The first alien is always Bilaterus, as I worked out through prior knowledge.
 * 3) As soon as a fish reaches big size, get both food quality upgrades and a few food quantity upgrades, and make Presto Meryl.
 * 4) Don't buy anything until all purchase options become available. At this point, I can feel free to make Presto Blip when an alien invasion is coming near (I can't do this before because his presence unlocks all purchase options, causing money inflation to start sooner). From what Blip shows me, I can work out which aliens are coming and turn Presto into the right pet for the job.
 * 5) Save up for an ultravore, and get it alongside a carnivore. To save money, always buy replacement carnivores as soon as a replacement is necessary.
 * 6) Keep saving money until I can afford the egg piece, then get the egg piece and save up to buy six weapon upgrades.
 * 7) Then, get a second Breeder, and a few more ultravores (this may happen during the process of weapon upgrades).
 * 8) Save up for the second egg piece.
 * 9) Get the last few weapon upgrades, then go for the final egg piece.

I may change this tactic if re-attempts fail.